KUHN GMD 400, GMD 400 HD, GMD 500, GMD 500 HD Operators Manual

ASSEMBLY / OPERATOR'S MANUAL

GMD 400 - 500

GMD 400 HD - 500 HD

MULTIDISC MOWER

N° 95001 C.GB - 03.2003

DEAR OWNER,

In buying a KUHN machine you have chosen wisely. Into it have gone years of thought,
research and improvements. You will find, as have thousands of owners all over the world, that
you have the best that engineering skill and actual field testing can produce. You have
purchased a dependable machine, but only by proper care and operation can you expect to
receive the performance and long service built into it.

This manual contains all the necessary information for you to receive full efficiency from your
machine. The performance you get from this machine is largely dependant upon how well you
read and understand this manual and apply this knowledge. Please DO NOT ASSUME THAT
YOU KNOW HOW TO OPERATE AND MAINTAIN YOUR MACHINE before reading this
manual carefully. KEEP THIS MANUAL AVAILABLE FOR REFERENCE.

Your KUHN dealer will instruct you on the general operation of your machine. He is interested
that you get the best performance possible and will be glad to answer any special questions
that may arise regarding the operation of the KUHN machine.

Your KUHN dealer can offer a complete line of genuine KUHN service parts.
These parts are manufactured and carefully inspected in the same factory that builds the
machine to assure high quality and accurate fitting of any necessary replacements.

When ordering service parts it is important that you indicate the type of machine concerned
and its serial number.

For this reason please complete the model identification plate diagram below with the required
information. This will provide you with an easy reference for future service parts orders.

ABOUT IMPROVEMENTS

KUHN is continually striving to improve its products and, therefore, reserves the right to make

improvements or changes when it becomes practical to do so, without incurring any
obligations to make changes or additions to the equipment sold previously.

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CONTENTS

Safety 2
Safety decals 9
Assembly instructions 11
Technical specifications 12
General information 17
Fitting to the tractor 18
P.T.O. shaft 20
Working position and adjustments 21
Transport and parking the machine 24
Operating the mower 25
Lubrication 26
Adjustments and maintenance 28
Optional equipment 33
Trouble shooting guide 3 5
Storing the mower 36
Limited warranty 38

Copyright 2003 KUHN S.A.

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SAFETY

The symbol above is used throughout this manual every time recommendations are made concerning your safety,
the safety of others, or the good operation of the machine.
These recommendations must be made known to all machine operators.

DESIGNATED USE OF THE MACHINE

The GMD 400 - 500 - 400 HD - 500 HD Disc Mowers must only be used for the work which they have been designed:
mowing on the ground of hay fields, grass silage fields and improved pastures for the purpose of harvesting fodder
for feeding livestock.

The manufacturer is not held liable for any damage resulting from machine applications other than those specified
by the manufacturer.

Any use other than the designated operation is at the risk and responsibility of the operator.
Designated use of the machine also means :

- following operation, maintenance and repair recommendations given by the manufacturer ;

- using only genuine spare parts, equipment and accessories as designated by the manufacturer.
The GMD 400 - 500 - 400 HD - 500 HD Disc Mowers must only be operated, maintained and repaired by competent

persons who are familiar with machine specifications and operation and are aware of any danger involved.
The operator must imperatively respect current legislation concerning :

- accident prevention,

- work safety,

- public traffic circulation.
All safety advice indicated on the machine must be strictly observed.
The manufacturer is not held liable for any damage resulting from machine modifications carried out by the operator

himself or by a third party without previous written agreement from the manufacturer.

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GENERAL SAFETY RECOMMENDATIONS

Before operating the machine, always ensure that tractor and machine are in accordance with work safety and
road traffic regulations.

BASIC PRINCIPLES

1. In addition to the recommendations given in this manual, legislation on work safety and accident prevention
must also be respected.

2. Advice is indicated on the machine, specifying safety recommendations in order to prevent accidents.

3. Before travelling on public roads, the operator must ensure that the machine conforms to road traffic
regulations.

4. Before starting work, the operator must be familiar with all machine controls, handling devices and their
functions. Once at work, it is too late to do so !

5. Use a tractor equipped with a safety cab. Keep windows and roof hatch closed for reduced sound level while
operating the PTO driven implement.

6. Before starting up the machine and beginning work, check the surrounding area (beware of children !). Make
sure there is sufficient visibility. Keep all people and animals away from the danger zone of the machine (risk
of projection!).

7. Carrying people or animals on the machine when working or in transport is strictly forbidden.

8. Machine must only be attached to tractor using means provided and in accordance with current safety
standards.

9. When attaching or removing the machine, place the parking stand into the corresponding position.

10. Special care should be taken when attaching or removing the machine from the tractor.

11. Before attaching the machine, ensure that the front tractor axle is sufficiently ballasted.
Ballast is to be placed on the supports provided in accordance with instructions of the tractor manufacturer.

12. Do not surpass the maximum axle load or the overall transport weight as prescribed by the tractor manufacturer.

13. Do not surpass the maximum transport width authorized by road traffic regulations.

14. Before transporting the machine on public roads, ensure that all legally required guards and indicators (lights,
reflectors ...) are in place and in good operation.

15. All operating controls (cords, cables, rods ...) must be positioned so that they cannot be set off accidently,
risking accident or damage.

16. Before transport on public roads, locate the machine into its transport position as instructed in this operator’s
manual.

17. Never leave the tractor seat while the machine is operating.

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18. Drive speed must be adapted to ground conditions as well as roads and paths.
Always avoid abrupt changes of direction.

19. Precision steering, tractor adherence, road holding and efficient braking are influenced by the type of
implement, weight, ballast of front axle, ground or road conditions. It is therefore of utmost importance to be
cautious in every given situation.

20. Be particularly cautious when turning corners, paying attention to machine overhang, length, height and weight.

21. Keep clear of the machine operating area.

22. WARNING ! Danger of crushing and shearing can exist when components are operated by hydraulic or
pneumatic controls.

23. Before leaving the tractor or before adjusting, maintaining or repairing the machine, turn off the engine, remove
ignition key and wait until all moving parts have come to a complete stop.

24. Do not stand between the tractor and the machine unless the hand brake is tight and/or stops have been placed
under the wheels.

25. Before any adjustments, maintenance or repairs are carried out, ensure that the machine cannot be started
up accidentally.

PRECAUTIONS TO BE TAKEN BEFORE OPERATING THE MACHINE

1. Do not wear loose clothing which could be caught up in moving parts.

2. Wear the individual protection equipment corresponding to the work which is planned (gloves, shoes, eye

protection, helmet, ear protectors...).

3. All operating controls (cords, cables, rods ...) must be positioned so that they cannot be set off accidentally,

causing accident or damage.

4. Before operating the machine, check the tightness of all nuts and bolts, particularly on rotating parts (blades,

tines, knives, spades ...)

5. Before operating the machine, ensure that all safety guards are firmly in place and in good condition. If worn

or damaged, replace immediately.

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ATTACHMENT

1. When attaching or removing the machine from the tractor, position hydraulic lift control lever in such a way that

it cannot be set off accidentally.

2. When attaching the machine to tractor 3-point linkage, ensure that diameter of link pins corresponds to diameter

of ball joints.

3. WARNING ! Danger of crushing and shearing can exist in the lifting zone of the 3-point linkage !

4. Do not stand between the tractor and the machine when operating the outer control lever of the lift mechanism.

5. In transport, the machine lift mechanism should be stabilized by tractor tie rods to avoid floatation and side

shifting.

6. When transporting the machine in the raised position, lock the lift control lever in place.

7. Do not operate the machine with narrow wheeltrack tractors when working or transporting on uneven or sloping

terrain.

POWER TAKE-OFF

1. Only use PTO shaft supplied with the machine or recommended by the manufacturer.

2. PTO guards must always be in place and in good condition.

3. Check for correct PTO overlap when at work and in transport.

4. Before attaching or removing the PTO shaft, disengage PTO shaft, turn off engine and remove ignition key.

5. If a primary PTO shaft is equipped with a slip clutch or a free wheel, these must be fitted on the machine PTO.

6. Ensure that PTO shaft is always correctly fitted and locked into place.

7. Make sure guards are correctly in place and secured with the safety chains provided.

8. Before engaging PTO, ensure that PTO frequency and direction are in accordance with manufacturer's

recommendations.

9. Before engaging PTO, keep all people and animals clear from the machine.

10. Never engage PTO shaft when tractor motor is turned off.

- 6 -

11. Never surpass PTO angle recommended by the manufacturer.

12. WARNING ! Rotating elements can continue turning momentarily after PTO is disengaged. Keep clear until all

rotating elements are at a standstill.

13. When removing the machine, locate PTO shaft on the supports provided.

14. Fit safety cap on tractor PTO.

15. Replace any worn or damaged PTO guards immediately.

HYDRAULIC SYSTEM

1. WARNING ! Hydraulic system is under pressure (maximum working pressure : 200 bars/2900 psi).

2. When fitting hydraulic motors or cylinders, ensure that connections have been made correctly, as per

manufacturer’s instructions.

3. Before connecting hoses to the tractor hydraulics, ensure that tractor and machine circuits are not under

pressure.

4. It is strongly recommended that the operator marks the hydraulic connections between tractor and machine to

avoid making a wrong connection. WARNING ! Functions could be reversed (for example : lift/lower).

5. Regularly check the hydraulic hoses ! Replace the hydraulic hoses every 5 years. Damaged or worn hoses must

immediately be replaced .
When replacing the hydraulic hoses, make sure to use hoses with the specifications and quality recommended
by the manufacturer of the machine.

6. Should a leak be found, take all necessary precautions to avoid accidents.

7. Any liquid under pressure (particularly oil from hydraulics) can penetrate the skin and cause severe injury. If

injured, see a doctor immediately, there could be danger of infection.

8. Before any adjustments, maintenance or repairs are carried out, lower the machine, depressurize the circuit,

turn off the engine and remove ignition key.

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MAINTENANCE

1. Before checking any machine malfunction and before adjusting, maintaining or repairing the machine, disengage

PTO, turn off engine and remove ignition key.

2. Check tightness of nuts and bolts regularly. Retighten if necessary.

3. If the machine is raised, prop it up in a stable position before carrying out any maintenance work.

4. When replacing a working part, wear protection gloves and only use standardized tools.

5. It is forbidden to discard any oil, grease or filters. These must be given to waste disposal organisations to protect

the environment.

6. Disconnect power source before any work is done on the electric system.

7. Check safety guards regularly, particularly those that are subject to wear. Replace immediately if damaged.

8. Spare parts used must be in accordance with specifications and standards as defined by the manufacturer. Use

only genuine KUHN parts !

9. Before any electric welding is carried out on tractor or attached machine, disconnect generator and battery

terminals.

10.Repairs on elements under pressure or tension (springs, accumulators etc.) must only be carried out by

competent persons with standardized equipment.

SPECIAL SAFETY RECOMMENDATIONS

1. Use a tractor equipped with an enclosed cab with windows made of safety glass and kept closed. It is

recommended to fit polycarbonate screens inside the tractor safety cab's side and rear windows or to install mesh
guards on the exterior of them.

2. Stay a safe distance away from the mower when discs are rotating.

3. For safe machine operation, it is imperative that cutting tools be fitted in accordance with the manufacturer’s

recommendations. Use only the tool outfit supplied with the machine.

4. Each time before using the mower, inspect condition of cutting elements (knives, discs). Replace any missing,

worn or damaged cutting elements immediately. Use only genuine KUHN spare parts.

5. To avoid creating dangerous out of balance forces, always replace missing, damaged or worn knives in pairs.

- 8 -

6. When replacing knives or discs, systematically inspect their securing elements as per the manufacturer’s

recommendations.

7. Regularly inspect the disc mower’s protection cover. Worn or damaged protection covers must be replaced

immediately.

8. Protection devices (such as guards, shields etc.) are intended to prevent stones, rocks or other foreign objects

from being projected. They also prevent access to the machine’s danger zones. Therefore, it is imperative that
protection devices are put in place and properly secured each time before using the machine.

9. Crushing and shearing zones which could cause serious bodily injury when changing the machine from transport

to work position and vice versa may exist. To prevent possible injury, be extra careful when maneuvering and
ensure that everyone is at a safe distance away from the machine.

10.PTO drive to the mower must never be engaged unless the cutterbar skid shoes are in contact with the ground

and the protective cover is folded down.

11.Ground of the pastures to be mown must be free of foreign objects.

12.Even when the machine is used in accordance with it purpose, objects may be projected. It is therefore imperative

that everyone be kept away from the danger zone, that extra care is taken and that extra precaution (such as
safety indicators) be taken when mowing pastures alongside roads or near public areas (parks, schools etc.).

13.Never mow in reverse.

14.When disengaging the PTO drive, moving parts continue to rotate for some time. Wait for all moving parts to come

to a complete stop before approaching the machine.

15.If an obstruction is hit, stop the tractor immediately, disengage PTO drive, turn off engine, remove ignition key

and wait for all moving parts to come to a complete stop.
Check the entire machine for any damage before resuming work.

16.It is strongly recommended to have your machine checked by your dealer after each season, especially blades

and discs and their fixing devices (nuts, bolts etc.).

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SAFETY DECALS

THE FOLLOWING SAFETY PICTORIALS HAVE BEEN PLACED ON YOUR MACHINE IN THE AREAS
INDICATED. THEY ARE INTENDED FOR YOUR PERSONAL SAFETY AND FOR THE SAFETY OF THE
PEOPLE WORKING WITH YOU. THE TEXT SHOWN ON THEM GIVES THEIR PRECISE MEANING.
KEEP THE PICTORIALS LEGIBLE. IF THEY ARE NOT, REPLACE THEM.

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TECHNICAL SPECIFICATIONS

TYPE GMD 400 - 400 HD GMD 500 - 500 HD

Number of discs 4 5
Width of cut 1.60 m (5' 3") 2.00 m (6'7")
PTO power requirement 21 kW (28 hp) 25 kW (35 hp)
Disc frequency (at 540 min-1) 2986 min

-1

Width in transport position 0.23m (9") wider than tractor width *
Lift system hydraulic
Weight: - GMD 400 - 500 380 kg (836 lbs) 427 kg (939 lbs)

- GMD 400 HD - 500 HD 386 kg (849 lbs) 434 kg (955 lbs)
Bevel gearbox oil capacity 0.25 litre
Oil quality : SAE 80 W EP (GL4) 0.53 US Pint / 0.43 Imp Pint
Cutterbar oil capacity 1.4 litre 1.7 litre
Oil quality : SAE 80 W EP (GL4) 3.0 US Pint / 2.5 Imp Pint 3.6 US Pint / 3.0 Imp Pint

* Applicable if machine is attached in such a way that a 5 cm / 2" distance «A» is respected (see page 18).

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ASSEMBLY

To facilitate shipping of the GMD 400 - 500 - 400 HD - 500 HD disc mowers, certain parts or assemblies are partially
disassembled to reduce bulk. To assemble these parts proceed as follows :

1. Mounting chassis to cutterbar

Make sure that the bore of nylon bushings is clean and well greased. Remove protective paint from the front cover
of bevel gearbox where bushings make contact. Chock chassis. Pull parking stand (C) outwards and swing it down.
Attach chassis to cutterbar with 2 self-locking screws (B) (M 16 x 50) and 2 washers (A) (dia. 16.5 x 60) as shown
in photo 1 and figure 1. Torque : 30 daNm/220 ft.lbs.

For your safety be sure to chock chassis correctly.

2. Assembly of belt shield, belts and
hydraulic hose

- Install pawl (L) and manoeuvering cord (H) as shown

on photo 1.

- Install the inner belt shield (D) (photo 2) in place and

secure with the 3 spacer bolts (E) taped on the stop
chain Torque to 5 daNm / 40 ft.lbs.

- Install closing plate (F) equipped with elastic nut as

shown in photo 2.

- Attach the latch (L) tension spring (R) (photo 1) to the

inner belt shield at (O) (photo 2) using a split pin (dia.
4 x 22 mm) provided.

- Fix hose (Z) to cylinder using a hollow screw and a

copper washer on each side of the banjo joint
(photo 2).

- 13 -

- Install belts (G) (photo 2) on pulleys and tension

them by loosening the 2 nuts (N) and tightening nut
(S) (photo 3).

- Belt tension is correct if deflection does not exceed

10 mm (2/5") when belt is pressed upon with a force
of 3.5 daNm (8 ft.lbs) at mid distance between
pulleys.

- When correct tension has been obtained, tighten the

2 nuts (N) (photo 3).

3. Frame pipe and lift bracket assembly

- Attach outer belt shield (E) with 3 washers and 3 cap
nuts (I)(photo 4). Torque to 5 daNm / 40 ft.lbs.

- Assemble closing plate (F) (photo 2) and outer belt
shield with one self-locking screw (K) (M 8 x 16)
(photo 4).

- Attach lift bracket (C) (photo 6) using axle and split
pins provided.

4. Compensating spring, inner shoe and
inner swath board assembly

- Place the cutterbar in the vertical position. Connect
compensating spring rod (F) (photo 7) to frame pipe
using axle and 2 split pins provided.

- Attach frame pipe (A) (photo 5) to bevel gearbox
using 4 (M12x35) bolts (B). Tighten to 14 daNm/100
ft.lbs.

6

- 14 -

- Attach the inner swathboard (D) (photo 8 A) in place
using 4 (M10 x 20) round head bolts (E), 4 plain
washers and 4 self-locking nuts. Tighten all inner
swathboard bolts (T).

5. Installing outer disc with cone and outer swath wheel

- Fit inner shoe (I) by means of 4 cup square bolts (J)
(M 10 x 25) and 4 self locking nuts (M 10) (photo 8).

- On the GMD 500 - 500 HD attach the outer disc with

cone using 4 hexagon screws (M 12 x 20) and 4
conical spring washers (position the conical centre
at the top) so that its largest diameter is positioned
at a right angle in relation to the adjacent disc (see
pictorial opposite). Tighten at 12 daNm (90 ft.lbs).

- Attach swath wheel assembly (U) to outer skid shoe

(photo 9) with 2 cup square bolts (V) (M 12 x 35), 2
conical washers (dia. 13 mm) and 2 self-locking nuts
(M 12). Torque : 8.5 daNm/65 ft.lbs.
Before tightening screws (V), make sure that disc
does not come into contact with cone cover or
knives.
Keep to a distance of X = 15 to 25 mm / 5/8" - 1".

8A

9A

9

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The angular position of the swath wheel compared to the cutterbar can be adapted to working
conditions enabling a regular flow of the cut crop towards the rear.
Position the swath wheel so that maximum angle (A') (fig. 9 A) is obtained. In difficult working
conditions (long, dense, bent over crops) position it towards minimum angle (A) (fig. 9 A).

6. Safety guard and locking device assembly

- Attach the front safety bar (B) to its 2 hinges (C) with
the 3 cup square bolts (P) (M 10 x 25), 3 self-locking
nuts (O) (M 10) and 3 flat washers (Q) (diameter 11
x 24 x 2) (fig. 10).

- Then attach the pre-assembled front safety bar (B)
at (N) with 2 hexagonal screws (M 12 x 75) and self­locking nuts (M 12) (photo 11). Do not tighten these
2 screws completely, so that the front safety bar can
still pivot.

- Next attach rear safety bar (A) with 3 round head
bolts (P) (M 10 x 25), 3 self-locking nuts (O) (M 10)
and 3 flat washers (Q) (diameter 11 x 24 x 2) (fig. 10
and photo 11). Fit end-plug (Z) on rear safety bar
(A) (photo 11).

- 16 -

- Install cover (D) as shown in photo 12. Buckle straps around the pipe frame at E. Buckle straps (F) around front
and rear safety bar. All these straps are attached to the underneath of the safety cover.

- Punch 3 holes in the safety cover at (G) and use 3 cup square bolts (R) (M 10 x 35) with self-locking nuts (0)
(M 10) (fig. 10) and plain washers (Q) (dia. 11 x 24 x 2) to attach the following components on the outside arms
of the safety bars : safety guard locking device (S) ; safety cover (D) ; stop rod (J) (see fig. 10 and also refer
to photos 11, 12 and 13).

Note : Make sure that the pivot axis of the safety guard locking device (S) is lined up with the pivot axis (N) of the

front safety bar before tightening self-locking nuts (O).

Never operate the mower without the protection cover in place and the pivoting front
protector lowered. Do not lean against or stand on the guard cover.

The safety guard locking device is operated with an
18mm box spanner (T) to be stored in holder (U) (photo

14).

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GENERAL INFORMATION

1. Minimum tractor PTO power requirement should be
21 kW (28 hp) for the GMD 400 - 400 HD and
25 kW (35 hp) for the GMD 500 - 500 HD.
If the tractor engine rating is insufficient, quality of
work will not be satisfactory.

2. GMD 400 - 500 - 400 HD - 500 HD Disc Mowers
can only be operated on tractors equipped with a

standard 540 min-1 PTO frequency and a standard
category 1 or category 2 3-point attachment.

Category 2 lower link bushes (590 010 00) are
supplied with the machine for attachment to
tractors with category 2 linkages.

3. The GMD 400 - 500 - 400 HD - 500 HD are equipped
with adjustable lower link pins allowing the machines
to be offset 50 mm (2") to the left and to the right when
mounted to a category 2 linkage and 114 mm (4.5")
to the left when mounted to a category 1 linkage.
To adjust lower link pins A, unscrew counter nut (C)
and hexagon screw (B) (photo 15 and fig. 15 A).
Displace pins as shown in the following drawing and
retighten screws and nuts.

Never mow in stony or rocky
grounds.

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ATTACHING THE MOWER TO THE TRACTOR

ATTACHMENT OF LOWER LINKS AND
POSITIONNING OF LINK PINS :

Follow fig. 1 for category 1 tractors with narrow wheel

track.

Follow fig. 2 for category 1 tractors with wider wheel
track.

Follow fig. 3 for category 2 tractors with narrow wheel
track.

Follow fig. 4 for category 2 tractors with standard
wheel track.

Follow fig. 5 for category 2 tractors with wide wheel
track.

NOTE : Always attach machine in such a way that
distance A is approximately 5 cm (2") and make sure
that check chain (C) (photo 21, page 22) is always
correctly attached.

- 19 -

1. Attach the lower links to the hitch pins and secure
with linch pins shown at A (photo 16).

2. Attach the top link (B) using pin (C). Two positions
are available on the pin, depending on the diameter
of the ball joint, to secure the link to the mower .

3. Connect the hydraulic hose to the tractor.

4. Pressurize hydraulic cylinder to raise cutterbar until
it is automaticaly locked in the full vertical position.
Then release hydraulic pressure.

5. Raise the mower with the tractor hydraulics, pull out
parking stand (D) (photo 17) and pivot it 90° in the
direction of the arrow indicated in photo 17. Lock
stand in hole (E) during transport and field operation.

Note : Parking stand is pulled out easilly after

releasing hydraulic pressure as described in
point 4°.

- 20 -

P.T.O. SHAFT

Connect the PTO shaft to the 540 min-1 tractor drive (with the free wheel fitted on the machine side).
Make sure PTO length is correct :

1. When the PTO is in its maximum extended position, a minimum tube overlap of 150 mm (6") must be maintained.

2. When the PTO is in its maximum overlap position (retracted), tubes should not butt against the yokes. As a safety
measure a clearance of at least 1 cm (0.4") must be maintained. If this is not the case, shorten the two
transmission tubes and the two guard tubes by the same length (photos A and B). Bevel and clean the tubes (photo
C) and grease the inside of the outer tube (photo D).

3. Never operate the PTO at too great an angle (30° maximum) (photo 18).

These recommendations and adjustments must be respected to avoid damage or premature
wear of the PTO.

Never connect the PTO to the 1000 min

-1

tractor drive.

To avoid accidents which could be serious, make sure that the guards are always correctly
in place and secured with the safety chains (photos 18 and 19). Damaged guards should be
replaced immediately.

- 21 -

WORKING POSITION AND ADJUSTMENTS

Before putting the machine in work or transport position, ensure all persons are well clear of
the cutterbar pivoting area.

1. Pressurise the lift cylinder so that the cutterbar
closes up against its stop.

2. Pull cord (C) (photo 19) in order to free latch.

3. Lower the cutterbar down to the horizontal position
by releasing hydraulic pressure.

20

Release lock by applying pressure with the hand palm
(arrow 1) and fold front safety bar (V) downwards (arrow

2) (photo 20) till it is automatically locked in working
position.

- 22 -

Adjustment of chassis height from the ground :

1. Tractors equipped with 3-point linkage with position control function :

Set position control so that lower hitch pins are 400 mm (16") from the ground.

2. Tractors equipped with 3-point linkage without position control function (photo 21) :

- Lower machine until the left lower hitch pin (A) is 400
mm (16"), or slightly more, from the ground.

- Connect stop chain (C) with its hook supplied in the
hardware kit of the machine to one of the free holes
at the tractor’s top link attachment clevis. Make sure
the hook is free to pivot in line with the chain when
tension is applied.

- Lower the machine into working position. Chassis
height is correct when :

. The cutterbar is resting on the ground ;
. Stop chain (C) is tight ;
. E = 400 mm (16") (distance of lower hitch

pins from the ground).

- To keep this adjustment permanently, close hook
eyelet with roll pin (Ø 5 x 45 mm).

CUTTING HEIGHT

Maximum cutting height (50 mm / 2") (fig. 1) is achieved when the discs are parallel to the ground. Adjustment
of cutting height is achieved by altering the cutterbar tilt angle. This is effected by varying top link length (D)
(photo 21) until desired cutting height is achieved. To minimize blade and disc wear, improve grass regrowth
and get maximum nutritive value from the crop, minimum cutting height should never be adjusted less then
30 mm / 1 1/4" (fig. 2).

MAXIMUM CUTTING HEIGHT

MINIMUM CUTTING HEIGHT

Fig.1 Fig.2

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SAFETY BREAKAWAY

In rough field conditions the ground speed should be
reduced. A breakaway latch allows the cutterbar to
swing back if an obstruction is hit (photo 22).
IF THE LATCH RELEASES, STOP THE TRACTOR
IMMEDIATELY AND DISENGAGE THE PTO.
To reset the cutterbar, back the mower until the
cutterbar is in its normal position. Do not raise the
cutterbar to re-latch the breakaway. The factory setting
of the latch is adapted to most working conditions.

Note : Before using the mower, the break-away

linkage must be checked for good operation
making sure all components slide correctly
and are well greased. Check for any cutterbar
damage if an obstruction is encountered.

The stack of spring washers should be compressed to 96 mm (3 3/4") (photo 23). Observe carefully spring washer
arrangement as shown in fig. 3.
If after resetting, the cutterbar continues to break away, the pressure of spring assembly (A) (photo 23) can be
increased, but in all cases stacking must not be less than 91 mm (3 1/2"), as otherwise safety disengagement cannot
function.

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Before transporting the machine on the pu­blic highway, the operator should make sure
that the machine conforms to the highway
code.

TRANSPORT AND PARKING THE MACHINE

1° To transport the machine on public highways or from one field to another, proceed as follows :

- Disengage the PTO drive and wait for all movement to stop.

- Raise the machine with the tractor 3 point linkage.

- Release lock by applying pressure with the box spanner (A - arrow 1) supplied with the machine and fold the front

safety bar upwards (arrow 2) (photo 24) till it is automatically locked in transport position.

- Raise cutterbar in the vertical position. It will automatically be locked in place when it reaches the transport position

(photo 24 A).

Note : It is normal that the vent plug may seep lubricating fluid during the first activations of the hydraulic cylinder.

2° To park the machine proceed as follows :

- Be sure the cutterbar is in its vertical transport position.

- Pull out the stand (D) and bring it down (see arrow) until it automatically clicks into place (photo 24 B)

- Disconnect stop chain on tractor side.

- Pressurise the lift cylinder so that the cutterbar closes up against its stop.

- Pull cord in order to free latch of the cutterbar.

- Lower the cutterbar down to the horizontal position by releasing hydraulic pressure.

- With the hydraulic 3 point lift, lower the machine to the ground and disconnect the top link, the lower links and

then the hydraulic hose.

- Disconnect the PTO shaft (T) and support it with the stop chain (E) using hook (C) as shown in photo 24 B.

For your safety only park the machine with the cutterbar in the horizontal position.

- 25 -

Release lock by applying pressure with the hand palm
(arrow 1) and fold front safety bar (V) downwards (arrow

2) (photo 25) till it is automatically locked in working

position.

Ensure that the safety curtain is
completely in place around the
cutterbar.

Safety curtain will avoid projection of most foreign
objects.

Always allow a few minutes for oil to spread in the
cutterbar before engaging PTO when changing
cutterbar from transport to operating position.
Before cutting, engage tractor PTO and slowly increase
frequency up to 540 min-1.

OPERATING THE MOWER

25

Never mow in stony or rocky grounds.

Never operate the mower without the protection cover in place. Do not lean against
or stand on the guard cover.

Do not be disturbed by the high pitched whine of the discs. This will be reduced to some extent when cutting.
Forward speed must be adapted to working conditions and should be reduced when mowing dense crops.
Check correct fixation of plugs (C) (photo 25) on the outer and inner disc cone.
Replace immediately lost or worn plugs.

- 26 -

It is forbidden to discard oil, grease or filters of any type. These must be given to specialised
waste disposal organisations to protect the environment.

IMPORTANT

Imperatively change oil in : - cutterbar bevel gearbox

- cutterbar

after the first 10 hours of use [SAE 80 W EP (GL4)].
Thereafter, oil must be changed every 200 hours of work and at least once per year.

NOTE : Before draining oil, operate the cutterbar for a few minutes so that oil warms up.

LUBRICATION

GMD 400 - 400 HD GMD 500 - 500 HD

Quantity of oil in the bevel 0.25 litre / 0.53 US pint0.25 litre / 0.53 US pint
gearbox [SAE 80 W EP (GL4)] 0.43 Imp. pint 0.43 Imp. pint

Quantity of oil in the cutterbar 1.4 litres / 3 US pints

1.7 litres/3.6 US pints

[SAE 80 W EP (GL4)] 2.5 Imp.pints 3.0 Imp.pints

1. BEVEL GEARBOX

Plug (C) (photo 26) serves as a check plug when the
bar is horizontal. Remove plug (C). When oil level is

at its maximum, it will just begin to flow out of the hole.
Check oil level once a day. Add oil through filler plug

(B) (photo 26) if required.
The pressure relief valve (A) (photo 26) must be
checked and cleaned regularly. The ball detent must
be free to relieve pressure.
The maximum oil capacity of this gearbox is as shown
in the table below and it is important not to exceed

this quantity.

Plug (C) is also used as a drain plug when the
cutterbar is in the vertical transport position.

- 27 -

2. CUTTERBAR

Note : Make sure the cutterbar is in the vertical position

when checking, adding or changing oil.
The oil level is at its maximum when oil flows out of the
filler plug hole.

Check oil level once a day. Add SAE 80 W EP (GL4)
oil to the cutterbar at filler plug (D) (photo 27).

To drain oil, remove magnetic drain plug (E) (photo 27)
located underneath the cutterbar below the bevel
gearbox.
Clean all metal particles off the magnetic drain plug
before refitting.

NOTE : Provided above intructions are strictly observed,
there is no cause for alarm if it is found that the
transmission case is very hot to touch, provided that the
discs turn freely by hand. .

Attention : Before carrying out this check, turn off
the tractor engine, remove ignition key and dis­connect the PTO shaft.

3. PTO SHAFT

Lubricate the PTO shaft at the hourly intervals indicated
in figure 1 with SHELL Multi-Purpose grease NLGI
grade 2.

The recommended grease and oil change periods are based on normal field and work
conditions.
Severe or unusual conditions may require more frequent lubrication or oil changes.

RESPECT SPECIFIED OIL QUANTITIES AND GRADES : SAE 80 W EP (GL4) OIL ONLY.

4. GREASE FITTINGS

Clean fittings before applying grease. Oil all pivot and linkage points every fifty hours.
Grease breakaway sliding components as required.

1

[In certain countries SAE 80 W EP (GL4) oil may not be available. In this case a GL4 or GL5 grade
SAE 80 W 90 oil may be used as a replacement. Never use a straight EP 90 oil].

- 28 -

Discs, knives and securing elements are manufac­tured from high quality steel and have been subjected
to a heat-treatment to assure a high resistance to wear.

Worn or damaged items must immediately be
replaced with genuine KUHN parts as otherwise
warranty will be withdrawn.

ADJUSTMENTS AND MAINTENANCE

CAUTION : Before carrying out service or adjustments to the machine, turn off the tractor
engine, remove ignition key and disconnect the PTO shaft.

Adjust machine to clear obstructions and debris. Foreign objects and other debris can be
deflected toward the operator and bystanders.

1. INSPECTION OF KNIVES AND SECURING ELEMENTS

A) KNIVES : should be inspected systematically

each time before the machine is operated.

Cutting quality as well as safe operation depend on the
regular inspection and care given to the knives. Knives
should be replaced in the following cases :

a) Damaged knives

Very rough conditions can cause knives to crack
and become deformed leading to :

- increased risk of accidents ;

- deterioration of cutting quality ;

- risk of damage to the cutterbar.

b) Worn knives

Length (A) of a knife should be greater than 65 mm.
The width (B) of a knife, measured at a distance
of 10 mm away from the edge of the disc should
be greater than 34 mm.

The hole (L) for the securing bolt must not become
oval by more than 20 mm for an 18 mm hole.

- 29 -

B) SECURING ELEMENTS : To be inspected

regularly !

(particularly the tightening torque of the nut:
12 daNm / 90 ft.lbs).

- Inspect immediately after hitting an obstruction.

- Inspect when replacing knives.

- Check at the beginning of each season.

a) The securing bolt must be replaced :

- When a visible deformation is found.

- When the locking compound on the threads has

worn away or if the locking compound has become
inoperational due to inclusion of water, oil or dirt.

- When wear on the head reaches the contact area of

the knife.

- When the diameter (D) of the bolt shoulder is less

than 15 mm (5/8 ").

b) The nuts must be replaced :

- When the contact washer has lost its elasticity or

when it becomes loose from the nut.

- When wear on the nut reaches a = 5 mm.

FOR THE CORRECT OPERATION OF YOUR MACHINE,

ALWAYS USE GENUINE KUHN SPARE PARTS.

- 30 -

2. KNIFE REPLACEMENT

To replace knives, first clean the area around nut (A)
(photo 28) and remove nut with the box spanner (T)
supplied with the machine. To facilitate the removal of
the nut, we recommend to place a block of wood (Z)
between 2 discs to stop them from rotating (photo

28). Remove the bolt (W) through the hole located at

the front of the disc guard (photo 29).
Ensure securing elements are in good condition and fit
knives so that the arrow on their upper face is pointing
in the direction of rotation of the disc (fig. A) it is fitted
to.

Torque locknut to 12 daNm / 90 ft.lbs.

28

29

Fig. A

GMD 400
GMD 400 HD

GMD 500
GMD 500 HD

- 31 -

Important : Always replace securing elements (lock-nuts and bolts) when they have been
removed 5 times.

Caution : Always replace damaged knives, never straighten a bent knife.

Never replace one knife only per disc, always replace both of them to avoid creating an out­of-balance force.

3. DISCS REPLACEMENT

To replace a disc, place a block of wood (Z) between
two discs to stop them from rotating. Unscrew the 4
nipple-screws (B) with the box spanner (T) supplied
with the machine and take the 4 conical spring washers
(C) off (photo 30 and fig. C).
Two of these diametrically opposite bolts are also used
to secure the conical covers on top of the discs.
When remounting must the discs have their largest
diameters positioned at right angles to each other. This
positioning must be scrupulously respected so as to
avoid interference between the knives.
Take extra care when fitting the conical spring washers
(C) (fig. C), which must be positioned with the conical
centre at the top.

Tighten bolts to a torque of 12 daNm (90 ft.lbs).

THE GMD 400 / 500 DISCS SUPPLIED
THROUGH OUR SPARE PARTS
DEPARTMENT COME WITH A 1 MM
SPACER (PART no. 568 071 00) (fig.
B) ATTACHED TO THEM. WHEN
INSTALLING A NEW DISC CHECK
IF THE GAP BETWEEN THE
BLADES OR THEIR MOUNTING
BOLTS AND THE CUTTERBAR PRO­TECTION SHIELDS IS AT LEAST 1
MM. IF THIS IS NOT THE CASE FIT
THE 1 MM SPACER BETWEEN THE
DISC AND ITS MOUNTING HUB FOR
INCREA-SED CLEARANCE (fig.
B).THIS SPACER IS NOT

REQUIRED ON DISCS FOR GMD
400 HD - 500 HD.

Dull knives require more horse power to cut the crop
and will leave an uneven stubble.
Worn knives should either be turned over on the same
disc to use the other cutting edge, or replaced. When
turning or replacing the knifes, make sure there is a 1
mm minimum gap between the knives or their mount­ing bolts and the cutterbar wear plates. If otherwise,
insert one (maximum two) distance spacer(s) (code
568 071 00) between the discs and the disc bearing
stations (fig. B) (only for GMD 400 - 500) .

Fig. C

30

Fig. B

Regularly check all nuts and bolts for correct tightness, particularly those securing
discs and blades.

- 32 -

2. BELTS

The belts must be properly tensioned at all times to
prevent excessive slipping and flopping. Loose belts
will also cause poor cutting and premature failures.
To tension the belts, loosen the 2 nuts (A) and tighten
nut (B) (photo 31). When belts have been tensioned
correctly, retighten nuts.

Belt tension is correct if deflection does not exceed 10
mm (2/5") when belts are pressed upon with a force
of 3,5 daN (8 lbs). This must be checked regularly and
particularly during the first hours of work. Access to
the belts is provided through the cut-out (C) located
underneath the safety guard (photo 31A).

Note : Only replace belts as a complete set

- No. 831 016 72 (GMD 400 - 400 HD)

- No. 831 016 73 (GMD 500 - 500 HD).

- 33 -

1. Hydraulic adaptators (photo 32)

For fitting to different types of hydraulic connectors,
three adaptators are available :
M16 x 1,5 / 1/2 GAZ - CON 22 (823 012 05)
M16 x 1,5 / 1/2 NPT - 24 (823 012 06)
M16 x 1,5 / 3/4 UNF - JIC (823 019 02)

2. Special PTO shaft (photo 33)

A reinforced PTO shaft including a free-wheel (No.
4500 560) is available for the following cases :

- When the standard PTO shaft is too short.

- When the tractor is equipped with a hydraulic PTO

break.

- When the angle of the PTO shaft is in excess of 25°

when working.

3. Kit for mowing at 40° below horizontal

(photo 34)

The kit (No. 102 6050) consists of a longer hydraulic
cylinder (V) and a shorter attachment rod to be mounted
in place of the original hydraulic cylinder and attach­ment rod.
When installing this kit, be sure to hook the suspen­sion spring (R) into the last hole of the bar (S) in order
to avoid too much tension when the slope exceeds
minus 30° (see photo 34).

OPTIONAL EQUIPMENT

- 34 -

4. Wear plate (568 017 00)

To prolong the life of worn disc guards when working in
very difficult and abrasive conditions, wear plates are
available through our spare parts department for welding
to the underside of each individual disc guard(fig. 35).

5. Raised skids (fig. 36)

Kit No. 103 6230

A raised skid shoe kit comprising 2 raised skids is
available as an optional equipment. This kit serves 2
purposes :

- providing a cutting height adjustable between
35 mm and 90 mm (1.5" and 3.5"),

- operating on sticky grounds.

These 2 raised skids are installed instead of the 2
regular end skids.

6. Signalling elements (photo 37)

Kit No. 102 6100

Signalling elements can be ordered as an optional
extra. To install this kit proceed as follows :

- Attach tail lamp (N) to panel (A).

- Bolt panel (A) to support (S) with 3 hexagon screws
(E) (M 10 x 20), 3 plain washers (dia. 11 x 24 x 2) and
3 self-locking nuts (M 10).

- Attach guide (H) to the rear guard tube (T) with an U­bolt and 2 self-locking nuts (L) (M 10).

- Plug electric cable (O) into the lamp terminal (N).

In transport position mount the panel (A) with its
support (S) in the guide (H) with lock (U) and plug
electric cable at the rear of the tractor.

Before putting the machine in
work position, dont forget to
unbolt the panel.

- 35 -

SERVICE ADJUSTMENT CHART

PROBLEM CAUSE REMEDY

Uneven stubble Too much tilt on cutterbar Reduce tilt (see page 22)

Low PTO frequency Increase engine frequency to run PTO

at 540 min

-1

Knives not installed Make sure that the arrow on the knife
correctly upper face is pointing in the direction

of rotation of the disc - see page 30)

Low disc frequency Check belts for correct tension

(see page 32)

Dull or broken knives Replace knives (see page 30)

Stubble too long Incorrect angle on cutterbar Change cutterbar angle using

tractor top link (see page 22)

Soil built up in front of Very wet conditions Adjust main frame height by
cutte rbar Excessive cutterbar shortening chain as necessary

downward pressure (see page 22)
Sticky ground Fit a set of raised skids (see page 34)

Cutterbar not floating Main frame setting incorrect Adjust main frame as described

on page 22

Machine breaking back Insufficient tension on Tighten breakaway spring
too easily breakaway spring washers washers (see page 23)

- 36 -

STORING THE MOWER

. Store the mower in a dry place.
. Thoroughly clean the mower.
. Drain oil from gearbox and cutterbar and refill with clean oil to correct level.
. Inspect and replace worn knives and their fixation hardware.
. Store cutterbar in operating position.
. Untighten drive belts.
. Clean bar and rusted areas and paint all areas from which the paint has worn.

- 37 -

SOUND LEVELS

Sound levels given out by : GMD 400 - GMD 500 - GMD 400 HD - GMD 500 HD Multidisc Mowers

Sound levels have been measured in accordance with the measuring methods as defined in:

EN 1553

<< Agricultural machinery - Agricultural self-propelled, mounted, semi-mounted and trailed machines -

Common safety requirements >>
The tractor used has an engine power of 92 kW.
A-weighted emission sound pressure level L (A) eq inside tractor cab (with closed windows) :

GMD 400 - 400 HD GMD 500 - 500 HD

Tractor only 69.8 dB (A) 69.8 dB (A)

Tractor + machine 72.0 dB (A) 72.1 db (A)

LIMITED WARRANTY

KUHN S.A. of 4 Impasse des Fabriques, 67706 SAVERNE CEDEX, France (hereinafter called the

«Company») warrants, in accordance with the provisions below, to each original retail purchaser of
KUHN new equipment of its own manufacture, from an authorized KUHN dealer, that such equipment
is, at the time of delivery to such purchaser, free from defects in material and workmanship and that
such equipment will be warranted for a period of one year starting from the date the goods are delivered
to the end user and during this period up to a limit of 500 hours use, providing the machine is used and
serviced in accordance with the recommendations in the Operator’s Manual.

THESE CONDITIONS ARE SUBJECT TO THE FOLLOWING EXCEPTIONS :

1. Parts of machines which are not of our manufacture i.e. tyres, belts, P.T.O. shafts, clutches etc., are not

covered by this Limited Warranty but are subject to the warranty of the original manufacturer. Any claim
falling into this category will be taken up with the manufacturer concerned.

2. Warranty claims applying to these types of parts must be handled in the same way as if they were parts
manufactured by KUHN. However, compensation will be paid in accordance with the warranty agree­ment of the manufacturer concerned in as much as the latter justifies such a claim.

3. This Limited Warranty will be withdrawn if any equipment has been used for purposes other than for
which it was intended or if it has been misused, neglected or damaged by accident or let out on hire. Nor
can claims be accepted if parts other than those manufactured by us have been incorporated in any of
our equipment. Furthermore, the Company shall not be responsible for damage in transit or handling by
any common carrier and under no circumstances within or without the warranty period will the Company
be liable for damages for loss of use or damages resulting from delay or any consequential damage.

We cannot be held responsible for loss of earnings caused by a breakdown or for injuries either to the owner
or to a third party, nor can we be called upon to be responsible for labor charges, other than originally
agreed, incurred in the removal or replacements of components.

THE CUSTOMER WILL BE RESPONSIBLE FOR AND BEAR THE COSTS OF:

1. Normal maintenance such as greasing, maintenance of oil levels, minor adjustments, etc.

2. Transportation of any kind of any KUHN product to and from the place the warranty work is performed.

3. Dealer travel time to and from the machine or to deliver and return the machine from the workshop for

repair.

4. Dealer travelling costs.

Parts defined as normal wearing items are listed as follows and are not in any way covered under this
Limited Warranty :
V belts, discs, knives, wear plates, disc guards, tires, torque limiters, hydraulic hoses, pitman shafts, swath
sticks, blades, tines and tine holders.

KUHN Limited Warranty will not apply to any product which is altered or modified without the expressed
permission of the Company and/or repaired by anyone other than Authorized Service Distributors or
Authorized Service Dealers.

LIMITED WARRANTY IS DEPENDENT UPON THE STRICT OBSERVANCE BY THE
PURCHASER OF THE FOLLOWING PROVISIONS :

- That this Limited Warranty shall not be assigned or transferred to anyone unless the Company’s consent in

writing has first been obtained.

- The warranty/product registration form has been correctly completed by dealer and purchaser with their

names and addresses, dated, signed and returned to the appropriate address as given on the warranty/
product registration form.

- The claim form sent to KUHN has been correctly completed stating:

* dealer’s name and address
* owner’s name and address
* type of machine
* machine serial number
* delivery date to buyer
* date of failure
* tractor make and type
* description of the failure and its cause
* quantity, reference number and name of the damaged part s
* reference number, quantity and date of the invoice for the replacement parts.

- The judgement of the Company in all cases of claims under this Limited Warranty shall be final and conclu-

sive and the purchaser agrees to accept its decisions on all questions as to defect and to the exchange of
any part or parts.

- That all safety instructions in the Operator’s Manual shall be followed and all safety guards regularly inspected

and replaced where necessary .

No warranty is given on second-hand products and none is to be implied. Persons dealing in the Company’s
products are in no way legal agents of the Company and have no right or authority to assume any obligation
on their behalf, express implied, or to bind them in any way .

KUHN S.A. reserves the right to incorporate any change in design in its products without obligation to make
such changes on units previously manufactured.

Moreover, because of the constant progress in technology, no guarantee is given to the descriptions of
equipment published in any document by the company .

DISCLAIMER OF FURTHER W ARRANTY

There are no warranties, expressed or implied, except as set forth above. There is no
warranty of merchantability. There are no warranties which extend beyond the description
of the product contained herein. In no event shall the company be liable for indirect, special
or consequential damages (such as loss of anticipated profits) in connection with the retail
purchaser’s use of the product.

- N O T E S -

This machine complies with the safety requirements of the European machinery directive.

The Operator should respect all Health and Safety regulations as well as the Highway
Code. For your own safety, use only genuine KUHN spare parts. The manufacturer
disclaims all responsibilities due to incorrect use or non-compliance with the
recommendations given in this manual.

Printed in France by KUHN

KUHN S.A. 4 Impasse des Fabriques F - 67706 SAVERNE CEDEX (FRANCE)

Tél. : + 33 (0) 3 88 01 81 00 - Fax : + 33 (0) 3 88 01 81 03

www.kuhnsa.com - E-mail : [e-mail]

Société Anonyme au Capital de 19 488 000 Euros

For your safety

and to get the best from your machine,

use only genuine KUHN parts