Universal Air Tools UT8750B User Manual

Read these instructions carefully before installing, operating,
servicing or repairing this tool. Keep these instructions in a safe

Includes - Foreseen Use, Work Stations, Putting Into Service, Operating,

Operator Instructions

Angle Disc Grinder

UT8750A - 4½” Disc (115mm)

Tel No

[phone]

Test Method

Tested in accordance with Pneurop

test code PN8NTC1 and ISO Standard 3744

Vibration Level

Test Method

Tested in accordance with ISO

5.1

Important

Dismantling, Assembly and Safety Rules

Manufacturer/Supplier Product Type

Universal Air Tool Company Limited
Unit 8
Lane End Industrial Park
High Wycombe
Bucks

accessible place.

RPM

12,000

10mm Dia Threaded Shaft

Cycles Per Min

Model No/Nos Serial No

UT8750 - 4” Disc (100mm)

HP14 3BY

Fax No

[phone]

Product Nett Weight

3.87

1.76 3/8 10 30 10

Recommended Working
Recommended Minimum
Maximum

Use - Safety Glasses
Use - Safety Gloves
Use - Safety Boots
Use - Breathing Masks
Use - Ear Protectors

lbs
Kg

Air Pressure

Personal Safety Equipment

Recommended Use Of

Balancer Or Support

No

bar

6.3
n/a

7.0

bar
bar

90

n/a

100

Yes
Yes

Yes
Yes

UT8750B - 5” Disc (125mm)

Recommended Hose Bore

Size - Minimum

Ins M/M Ft M

Noise Level

PSI
PSI
PSI

Sound Pressure Level 82.9 dB(A)

standards 8662/1 & 8662/4

Recommended Max.

Hose Length

Metres / Sec²

Foreseen Use of Tool

This right angle grinder is designed to be used with reinforced resin
bonded depressed centre grinding wheels that have a permitted
rotational speed in excess of 12,000 RPM. See parts lists for details of
available wheel sizes.
The tool is designed to be used for light grinding and dressing of welds,
etc. but not for cutting off. The grinder must never be used if a wheel
guard (disc cover) item (3) is not fitted.

Work Stations

The tool should only be used as a hand held hand operated tool. It is
always recommended that the tool is used when standing on a solid
floor. It can be used in other positions but before any such use the
operator must be in a secure position having a firm grip and footing and
be aware of the safety rules to be obeyed when using the sander.

Putting Into Service

Air Supply

Use a clean lubricated air supply
that will give a measured air
pressure at the tool of 90 p.s.i./6.3
bar when the tool is running with
the trigger/lever fully depressed.
Use recommended hose size and
length. It is recommended that the
tool is connected to the air supply
as shown in figure 1. Do not

connect the tool to the air line system without incorporating an easy
to reach and operate air shut off valve. The air supply should be
lubricated. It is strongly recommended that an air filter, regulator,
lubricator (FRL) is used as shown in Figure 1 as this will supply
clean, lubricated air at the correct pressure to the tool. Details of
such equipment can be obtained from your supplier. If such
equipment is not used then the tool should be lubricated by
shutting off the air supply to the tool, depressurising the line by
pressing the trigger on the tool. Disconnect the air line and pour into
the intake bushing a teaspoonful (5ml) of a suitable pneumatic
motor lubricating oil preferably incorporating a rust inhibitor.
Reconnect tool to air supply and run tool slowly for a few seconds
to allow air to circulate the oil. If tool is used frequently lubricate on
daily basis and if tool starts to slow or lose power.
It is recommended that the air pressure at the tool whilst the tool is
running is 90 p.s.i./6.3 bar. The tool can run at lower and higher
pressures with the maximum permitted working air pressure of
100 p.s.i./7 bar.

Page No 1

Operating

With the grinder correctly connected to the air supply, check the speed
of the grinder with an inlet pressure of 100 psi/7.0 bar measured at the
tool inlet. Check with a calibrated tachometer. Check that the guard is in
position and securely fixed. Check that the grinding wheel is of correct
dimensions, is not cracked or chipped and has a permitted speed
rating higher than the maximum permissible running speed of the
grinder which is 12,000 RPM. Check that item 5 disc receiver is the
correct type as parts list and is screwed tightly to the shaft and locates
the bore of the grinding wheel on the spigot of the disc receiver and
screw on disc nut item (4) using the spanners provided. Do not over
tighten as this could crack the wheel. It should be tight enough to
prevent wheel spin off when the air supply is shut off.
When first starting the grinder with a new or changed wheel fitted, the
grinder should first be started in a protected area, i.e. such as under a
heavy bench well away from other persons and run for, say, one
minute. This will provide protection if the wheel should break because
some fault was not detected.
Always use eye protection and wear protective gloves if there are sharp
edges in the working area. The tool and the grinding process can create
a noise level such that ear protectors should be worn.
If the grinding process creates a dust then use a suitable breathing
mask.
Check that the material being worked will not cause harmful dust or
fumes. If this is so then special breathing apparatus may be required.
Seek advice before starting work.
If the grinder vibrates when first fitting the wheel or during use, remove
from service immediately and arrange for the fault to be corrected
before continuing to use.
Do not apply excessive pressure as this will reduce the cutting
efficiency. Apply light loads and allow the wheel to cut.
Handle the grinder with care. If the grinder is dropped, carefully
examine the wheel for damage and replace if necessary. Start the
machine as if for the first time of fitting a wheel, i.e. under a bench.
Make sure the object to be ground is in a firm fixed position.

Dismantling & Assembly Instructions

Disconnect tool from air supply.
Grip gear shaft (11) with spanner (41) and insert spanner (40) into the
holes in disc nut (4), unscrew disc nut (4) and take off grinding disc (34)
and disc receiver (5), remove 4 off screws (37) and take off disc cover
(3), retainer (7) and gasket (8). Pull out the drive shaft assembly from
body (1). Unscrew grip (6) from body (1) and remove 2 off screws (16)
and take off exhaust cover (48). Remove spacer (14).
Support bearing (14) and tap the non threaded end of the gear shaft
(11) to drive it through the bearing (14). Take off retaining ring (13) from
gear shaft (11) and support bearing (9) on the threaded shaft side and
press the non threaded end of gear shaft (11) through the assembly to
separate gear shaft (11), key (12), bearing (9), bevel gear (10) and
wave washer (43).
By holding body (1) in a vice fitted with soft jaws the control head
assembly may be removed from body (1) by unscrewing lock ring (50).
It is then possible to pull out the motor and governor assembly from the
body (1). Pull off pinion assembly from motor assembly and press apart
pinion (15) and bearing (18). Grip the front plate (20) by hand and with
a non metallic or soft metal (lead or aluminium) hammer tap the splined
end of rotor (24) to drive the rotor and the remainder of the motor and
governor assembly through the front plate and bearing assembly. Take
off the cylinder (23) noting its orientation for reassembly and take out 4
off rotor blades (25) from rotor (24). Spring pin (22) may be pulled out
of cylinder (23) if a replacement is required.
Grip rotor (24) in a vice with soft jaws and unscrew the governor
assembly from the rotor - left hand thread. Support the rear end plate
(26) in a piece of tube with a bore as close as possible to the maximum
diameter of the rotor and very carefully so as not to damage the thread,
tap the rotor through the rear end plate (26) and bearing assembly. With
a suitable punch tap out bearing (17) from rear end plate (26) and
bearing (17) from front plate (20).
To dismantle the governor assembly first unscrew adjust screw (42)
assembly. Take off spring (28). Drive out 2 off spring pins (47) and take
out 8 off pendulums (45) from governor (44). When removing the
pendulums take special note of the orientation to the governor (45) to
ensure they are fitted the same way on reassembly. This is important.

Grip valve housing (56) in a vice and remove O-ring (39) from lock ring
(50). Drive out pin (58) and take off safety throttle lever (60). Do not
dismantle the throttle lever (60). Unscrew bushing (57). Unscrew valve
nut (52) and remove with O-ring (53), spring (54), valve (59) and O-ring
(55).
Unscrew coupling nut (51) - left hand thread - from valve housing (56)
and unscrew lock ring (50) from coupling nut (51).and unscrew lock
ring (50) from coupling nut (51).

Reassembly

Clean all parts and examine for wear. Use only distributor or
manufacturer supplied spare parts. Particularly examine O-rings,
bearings and gears. Coat all parts in a pneumatic tool lubricating oil, one
preferably containing a rust inhibitor. Grease bearings and gears with a
molybdenum or lithium based general purpose grease. Reassemble in
the reverse order. See Note below.
For the motor make sure that the end plates that abut the cylinder are
free from burrs and sharp edges and if necessary lap on a flat fine grade
of abrasive paper. Press bearing (17) into rear case (26) and support the
inner race of bearing (17) and press the non splined end of rotor (24)
into the assembly. Tap the rotor relative to the rear case and bearing
assembly until a clearance of approx. 0.0025” (0.065mm) is achieved
between the rotor and the rear case. Ensure the rotor spins freely before
assembling the rest of the motor assembly.
This machine has a speed controller or governor, parts (21), (28), (42),
(44), (45) and (46). The correct setting of this speed controller is critical
to the safety of the tool and should only be carried out by a trained
competent person. The speed is set by assembling the speed
controller, measuring the output spindle gear shaft (11) speed with a
calibrated tachometer. Adjustment to the spindle speed can be made
by rotating adjust screw (42). The speed of the grinder running free with
an air inlet pressure of 100 psi (7 bar) measured at inlet bushing (57)
must not exceed 12,000 RPM.

Safety Rules For A Grinder

1) Read all the instructions before using this tool. All operators must be
fully trained in its use and aware of these safety rules.

2) Do not exceed the maximum working air pressure.

3) Use personal safety equipment.

4) Use only compressed air at the recommended conditions.

5) If the tool appears to malfunction remove from use immediately and
arrange for service and repair.

6) If the tool is used with a balancer or other support device ensure that
it is fixed securely.

7) Always keep hands away from the working attachment fitted to the
tool.

8) The tool is not electrically insulated. Never use the tool if there is any
chance of it coming into contact with live electricity.

9) Always when using the tool adopt a firm footing and/or position and
grip the tool firmly to be able to counteract any forces or reaction
forces that may be generated whilst using the tool.

10) Use only correct spare parts. Do not improvise or make temporary
repairs.

11) Do not lock, tape, wire, etc. the on/off valve in the run position. The
trigger/lever etc. must always be free to return to the ‘off’ position
when it is released.

12) Always shut off the air supply to the tool, and depress the
trigger/lever etc. to exhaust air from the feed hose before fitting,
adjusting or removing the working attachment.

13) Check hose and fittings regularly for wear. Replace if necessary. Do
not carry the tool by its hose and ensure the hand is remote from the
on/off control when carrying the tool with the air supply connected.

14) Take care against entanglement of moving parts of the tool with
clothing, ties, hair, cleaning rags, etc. This will cause the body to be
drawn towards the tool and can be very dangerous.

15) It is expected that users will adopt safe working practices and
observe all relevant legal requirements when installing, using or
maintaining the tool.

16) Do not install the tool unless an easily accessible and easily
operable on/off valve is incorporated in the air supply.

17) Take care that the tool exhaust air does not cause a problem or
blows on another person.

18) Never lay a tool down unless the working attachment has stopped

Page No 2