Demco 91 User Manual

DOING OUR BEST TO PROVIDE YOU THE BEST

MODEL 91

BRAKE ACTUA TORS

OWNER/OPERATOR MANUAL

1-04

BH20023, Rev 1

ASSEMBLY
CALIBRATION
OPERATION
REPLACEMENT PARTS

READ complete manual CAREFULLY

BEFORE attempting operation.

DEMCO  Dethmers Mfg. Co.  4010 320th St.  P.O. Box 189  Boyden, IA 51234

PH: [phone]  Toll Free: 1-800-543-3626  FAX: [phone]

www.demco-products.com

Page 1

DEMCO MODEL DA91 ACTUATOR

Model DA91 is a heavy duty surge brake actuator for trailers with two or four wheels.
When brakes are applied on the towing vehicle, forward inertia of trailer toward towing
vehicle applies brakes on trailer in direct relation to manner brakes are applied on
towing vehicle. Brake towing vehicle hard and brakes on trailer are applied hard.
Master cylinder push rod spring assembly protects system from hydraulic pressure
overload.

WARNING: To Prevent Serious Injury or Death

 Review following instructions before installation and use of hydraulic brake

actuator.

 Dealers or distributors must review these instructions with ultimate user.

 Failure to follow these instructions, or failure to properly maintain braking

system after installation, can result in loss of braking action.

Table of Contents

General Information ............................................................................................................2

Safety Sign Locations.........................................................................................................3

Bolt T orque .......................................................................................................................... 4

Bolt/Weight Rating W arning .................................................................................................5

Actuator Installation and Maintenance .............................................................................. 6-7

Demco Brake Products Limited Warranty ............................................................................ 8

Demco Brake Products Limited Warranty Cont....................................................................9

Actuator Parts Breakdown and Parts List...........................................................................10

Hitch Configurations...........................................................................................................11

Page 2

SAFETY SIGN LOCATIONS

Types of safety sign and locations on equipment are shown in illustration below. Good safety
requires that you familiarize yourself with various safety signs, type of warning, and area or
particular function related to that area, that requires your SAFETY AWARENESS.

This decal is positioned as shown

BRAKES ON

DO NOT TOW

Replacement Part #BH21003 Qty . 1

BRAKES OFF

TOWABLE

BH21003

Page 3

Tighten all bolts to torques specified in chart unless otherwise noted. Check tightness of bolts
periodically, using bolt chart as guide. Replace hardware with same grade bolt.

NOTE: Unless otherwise specified, high-strength Grade 5 hex bolts are used throughout assembly
of equipment.

Bolt Torque for Standard bolts *

Torque Specifications

Torque figures indicated are valid for
non-greased or non-oiled threads and
heads unless otherwise specified.
Therefore, do not grease or oil bolts or
capscrews unless otherwise specified
in this manual. When using locking
elements, increase torque values
by 5%.

* GRADE or CLASS value for bolts
and capscrews are identified by their
head markings.

GRADE 2 GRADE 5 GRADE 8

A lb-ft (N.m) lb-ft (N.m) lb-ft (N.m)

1/4 6 (8) 9 (12) 12 (16)

5/16 10 (13) 18 (25) 25 (35)

3/8 20 (27) 30 (40) 45 (60)

7/16 30 (40) 50 (70) 80 (110)

1/2 45 (60) 75 (100) 115 (155)

9/16 70 (95) 115 (155) 165 (220)

5/8 95 (130) 150 (200) 225 (300)
3/4 165 (225) 290 (390) 400 (540)
7/8 170 (230) 420 (570) 650 (880)

1 225 (300) 630 (850) 970 (1310)

Bolt Torque for Metric bolts *

CLASS 8.8 CLASS 9.8 CLASS 10.9

A lb-ft (N.m) lb-ft (N.m) lb-ft (N.m)

6 9 (13) 10 (14) 13 (17)
7 15 (21) 18 (24) 21 (29)

8 23 (31) 25 (34) 31 (42)
10 45 (61) 50 (68) 61 (83)
12 78 (106) 88 (118) 106 (144)
14 125 (169) 140 (189) 170 (230)
16 194 (263) 216 (293) 263 (357)
18 268 (363) -- -- 364 (493)
20 378 (513) -- -- 515 (689)
22 516 (699) -- -- 702 (952)
24 654 (886) -- -- 890 (1206)

GRADE-2 GRADE-5 GRADE-8

CLASS 8.8 CLASS 9.8 CLASS 10.9

8.8

9.8

Page 4

10.9

!

W ARNING: TO AVOID PERSONAL INJURY OR PROPERTY

DAMAGE, OBSERVE THE FOLLOWING INSTRUCTIONS:

The weight rating of the coupler is dependent on
the correct bolts being used. You must use the
bolts provided with the product. If you are miss­ing bolts, refer to your Operatorís Manual and ob­tain replacements from Demco, or use the exact
size, grade, and number of bolts as specified. Us­ing the wrong size, grade, or number of bolts will
reduce the weight rating of the coupler and could
cause separation of your towing equipment from
the towing vehicle. If you have questions about
the correct bolts for your application call Demco
at any of the following telephone numbers:

[phone]
[phone]
1-800-543-3626
FAX: [phone]

NOTE: disassembly of the actuator before welding is recommended

T ack Actuator down on the
four corners then weld in a
criss cross pattern using 2î
to 2-1/2î welds with 2î
spaces between welds
(when welding down to a
flat area of the tongue)

Do not weld in the
circled area

Keep braces
and welds
back to allow
access to
shock pin hole

Do not weld in the
circled area

WELDING

Use gussets to sup­port the back of the
actuator if welding in
position shown

Keep gussets
on rear of ac­tuator to lower
half to avoid
circled area

Weld as shown

Page 5

Keep braces and welds
back to allow access to
shock pin holes

DEMCO MODEL DA91 BRAKE ACTUATOR

WARNING

 Review all of the following instructions before installation and use of hydraulic brake
actuator.

 Dealers or Distributors must review these instructions with ultimate user.

 Failure to follow these instructions, or failure to properly maintain braking system after

installation, can result in loss of braking action which could cause severe property damage,
personal injury or death.

WARNING

To Prevent Serious Injury Or Death:

Model DA91 brake actuator has a maximum load rating of 8,000 lbs.
GVWR and 750 lbs. tongue load.

To avoid personal injury or death, do not exceed lowest of (1) the rated

capacity of Model DA91 actuator, or (2) rated capacity of ball, hitch, and
coupler being used, or (3) trailer's Gross Vehicle Weight Rating (GVWR).

Model DA91 brake actuator has a maximum tongue load equal to 10% of
the maximum load rating.

INSTALLATION

(SEE PAGE 10 FOR BREAKDOWN AND REFERENCE NUMBERS)

Model DA91 is completely assembled and ready to bolt or weld into place.

1. Standard DA91 actuators come with a variety of mounting channels. (see Page 11)

2. Connect and tighten all brake lines.

3. Fill master cylinder (#21) with DOT 3 or 4 brake fluid.

4. Bleed brake system using a pressure-type brake bleeder or manually, as follows:
a. Remove two 5/16" hex head bolts (#13) and lock washers (#8) that hold lever guide

(#23) and flat emergency lever spring (#12). Remove lever guide and emergency lever spring.
Using short strokes, pull forward on emergency lever (#16), pumping master cylinder until
brake fluid within master cylinder stops bubbling.

b. Attach a bleeder hose to bleeder valve on one of the wheels and submerge other end of hose

into a transparent container partially filled with brake fluid. Loosen bleeder valve one turn
and, watching hose in transparent container, use emergency leverto pump master cylinder
as long as air bubbles continue to leave the hose. When bubbles stop, close bleeder valve,
move to next wheel, and repeat process until all brakes have been bled. (Note: Check fluid level
in master cylinder frequently while bleeding brakes (every 4 or 5 strokes). Refill as necessary
to keep level above half full.)

Page 6

5. Once bleeding is completed, refill master cylinder and attach cap (#17) securely. Replace
emergency lever spring, lever guide, lock washers and 5/16" hex head bolts.

6. Test brakes by pulling emergency lever (#16) forward until it locks into its second notch
position. (Lever should be approximately straight up.) Attempt to rotate wheels in a forward
direction. If any wheels rotate, brakes must be adjusted. To adjust brakes, release
emergency lever from locked position, set each wheelís brake adjustment up 2 or 3 notches
(per instructions in appropriate brake cluster manual). Repeat test procedure as necessary.

MAINTENANCE

1. Frequently check brake fluid level. (Fluid must be approved, clean, and uncontaminated.)

2. Make sure actuator mounting bolts are secure.

3. Inspect actuator, replace bent, worn, or damaged parts.

4. Be constantly aware of systems braking quality, make periodic checks as described in brakes ownerís
manual. Consult certified brake specialist to make necessary adjustments or repairs. Failure to do so
could result in loss of braking.

SERVICING THE EMERGENCY LEVER

(SEE PAGE 10 FOR BREAKDOWN AND REFERENCE NUMBERS)

If emergency lever (#16) of actuator is applied, it can be disengaged by using a screwdriver to lift
upward on front of flat emergency lever spring (#12) while pulling lever forward until released.
A thorough inspection of emergency lever, emergency lever spring, and cable with S-hooks is required.
Damaged parts must be replaced as follows:

a. Remove master cylinder (#21) and push rod assembly (#18). Be careful not to get dirt into

master cylinder. (A new Master Cylinder Gasket (#20) should be used when reinstalling.)

b. Remove Cable S-hook (#10) from emergency lever (#16), emergency lever guide (#23) and flat

emergency lever spring (#12), then pull lever out of actuator outer case (#7) through cross-slot
intop.

c. Install new emergency lever through cross-slot in top of outer case. Attach new emergency lever

spring and emergency lever guide.

d. Insert S-hook on emergency cable (#10) into hole in emergency lever(#16) and squeeze shut.
e. Add adequate brake fluid to master cylinder and bleed brake system per instructions 4-6 in installation

section.

Page 7

DEMCO BRAKE PRODUCTS - LIMITED WARRANTY

1. Extent and Duration of this Warranty:

Your Demco brake product is warranted to be free from defects in materials and workmanship under normal use
and service for a period of one year after date of purchase by original owner when properly installed, used and
maintained by purchaser.

When this Demco brake product is used as part of complete Demco braking system (actuators, brake lines, and
back plates), Demco warrants system to be free from defects in materials and workmanship for two years when
properly installed, used, and maintained by purchaser.

Any part of Demco brake system found to be defective in materials or workmanship will be repaired or replaced at
manufacturers option without charge for parts or labor to original owner.

2. Manufacturer and Warrantor of Trailer:

Dethmers Manufacturing Co.
4010 320th Street
P.O. Box 189
Boyden, IA 51234
[phone]

3. Repair or Replacement Procedure:

If your Demco brake product develops a defect during warranty period, promptly notify Dethmers Manufacturing
Co. customer service department. Until such notice is received, warrantor will not be responsible for any repair or
replacement.

Upon receipt of timely notice from you, warrantor will have a choice of options in replacing any part it determines
to be defective:

a) Warrantor may require you at your own expense to deliver or ship part to its factory or authorized

dealer. Any defective part will be repaired or replaced and returned to you or your authorized dealer
free of charge. Any part returned to warrantor and found not to be defective will be returned to you
freight collect with explanation.

b) Warrantor may ship a new part to dealer to be exchanged free of charge for defective

part returned by you.

c) Warrantor may ship or deliver a replacement part to you at your address.

4. Limitations on Warranty Coverage:

Coverage under this warranty will be effective only when a copy of original invoice, showing date and location of
purchase, accompanies any claim for warranty.

Warrantor has no liability whatsoever and this warranty is null and void if any Demco brake product has been
misassembled or subjected to damage or neglect, negligence, misuse, accident or operated in any way contrary
to operating and maintenance instructions as specified in Demco owners manual for that product.

This warranty does not cover any product that has been altered or modified so as to affect the productís
operation, performance or durability, or that has been modified to change intended use of product.

In addition, warranty does not extend to repairs made necessary by abnormal use, damage, unreasonable
use including failure to provide reasonable and necessary maintenance, or by use of parts, accessories or
other equipment which are incompatible with Demco brake products or affect its operation, performance
or durability.

Page 8

DEMCO BRAKE PRODUCTS - LIMITED WARRANTY CONTINUED

This warranty does not cover:
a) normal wear and tear.
b) road film or gravel damage to paint.
c) paint.
d) rust damage.
e) any Demco brake product that has been loaded in excess of load capacity stated on identifica­ tion label.
f) Accessory parts, materials or components.

Warrantor has a policy of continuous product improvement. We reserve the right to change or
improve design of any Demco brake product, including but not limited to state of the art changes,
without assuming any obligation to modify any product previously manufactured.

Warrantor assumes no responsibility to owner for loss of use of product, loss of time, inconve­nience or other damage consequential or otherwise, including, but not limited to expense forgaso­line, expense of transporting product to dealer and expense of returning product, mechanics travel
time, telephone, telegram, fax, overnight delivery, or postage charges, road service/towing
charges, rental during time warranty repairs are being performed, travel, lodging, loss or damage
to personal property or loss of revenue or earnings.

5. Limitations of Implied Warranties:
All implied warranties, if any, expire and terminate upon expiration of this warranty. Some states
do not allow limitation on how long an implied warranty lasts, so this limitation may not apply to
you.

6. Limitation of Consequential Damages:
Warrantorís responsibility under this warranty extends solely to repair or replacement of your
Demco brake product and its component parts. Warrantor does not assume responsibility for, nor
shall it be liable for, any special, incidental or consequential damages. Some states do not allow
exclusion or limitation of incidental or consequential damages, so above exclusion or limitation
may not apply to you.

7. Purchasers Rights:
This warranty gives you specific legal rights, and you may also have other rights which vary from
state to state.

8. Exclusive Warranty:
This is the only express warranty made by Dethmers Manufacturing Co. on your Demco product
and no agent, employee, or other person is allowed to change or add to this warranty.This war
ranty extends solely to repair or replacement of your Demco brake product and its component
parts. Warrantor does not assume any liability or responsibility not expressly covered by this
limited warranty.This warranty supersedes all prior warranties, written or implied.

DISCLAIMER

No other express warranty has been made or will be made on behalf of warrantor with respect to
Demco brake product or its instruction, operation, repair or replacement.Warrantor shall not be
responsible for damage, loss or damage to personal property, whether direct or indirect, and
whether arising in contract or tort.

Page 9

5398 Master Cylinder

Repair Kit (drum)

(gasket 09153 included)

ACTUATOR PARTS BREAKDOWN

**12

**10

23

13

8

8

17

14

14

18

5482 Master Cylinder

Repair Kit (disc)

(gasket 09153 included)

not included

2î Ball Coupler RATED

AT 6000#

4

28

2

29

2

1

5221

3

Coupler Repair Kit

Model 91 ACTUATOR PARTS LIST

REF.

NO. PART NO. QTY. DESCRIPTION

1. 05432 1 6000# 2" Ball Coupler (zinc plated)

2. 01896 3 1/2"-13UNC x 4" Hex Head Bolt (gr.5)

3. 02178 3 1/2"-13UNC Nylon Insert Lock Nut

4. 05441-95 1 Front Shock Pin 5/8" dia x 3 (straight tube)

- 05426 1 Front Shock Pin (drop tube actuators)

5. 11078-?? 1 Straight Tube Actuator Slider

- 11079-?? 1 Drop Tube Actuator Slider

6. SB12426 1 Damper/ Shock

7. 11164-?? 1 3 Bolt Mount Outer Case

8. 05424 2 5/16" External Tooth Lock Washer

9. 02363 2 5/32" x 1 1/4 Cotter Pin(Qty 3 w/drop tube)

**10. 05408 1 3/32" Cable with hooks

11. SB10555 - Replacement S-Hooks ONLY

**12. 05693-?? 1 Emergency Lever Spring

13. 05961 2 5/16"-18UNC x 5/8" Hex Head Bolt (gr.5)

14. 00618 4 1/4-20UNC x 2" Hex Head Bolt (gr.5)

15. 00057 4 1/4" Lock Washer

**16. 05951-?? 1 Emergency Lever Assembly

17. 03876 1 Master Cylinder Cap w/ Diaphragm & O-ring

- 05849 1 O-Ring Only (not shown)

18. 05977 1 Push Rod Assembly

19. 00062 4 1/4-20 UNC Hex Nut

20. 09153 - Plastic Master Cyl. Gasket ONLY

21. 10616 1 Master Cylinder (drum brakes)

- 11190 - Master Cylinder (discbrakes)

22. SB12098 1 .018 Connector Orifice (Drum Brakes)

- 05679 1 Inverted Flare Adapter (Disc Brakes)

23. 03866-?? 1 Lever Guide

24. 05687 1 Master Cylinder Protective Boot

25. 05986-?? 1 Connecting Pin

26. 10965 1 Upper Slider

27. 10966 1 Lower Slider

28. 10967 2 Side Spacers

- 5401 - Lever Replacement Kit (incl. items w/**)

- 5650 - Master Cyl. Replacement Kit (drum)

- 5672 - Master Cyl Replacement Kit (disc)

- 5221 - Coupler Repair Kit

29. 02920 - Thumb Lock ONLY

11

**16

25

9

26

6

7

9

21

5

5

4

24

28

27

9

Optional Drop Tube

See Page 19 for additional Slider
Tube and Outer Case options

Slider

(OPTIONAL) FREE BACKING

SOLENOID KIT PARTS BREAK-

DOWN 5404 (FIELD INSTALL)

5629 (FACTORY INSTALL)

Remove Fitting (#22)
from Master Cylinder
and relocate to this hole

31

35

33

34

Drill the hole using a 5/32î bit. Hole location
is .900î right of top left corner and .900î down
from top of master cylinder. Tap hole with 10-32 NF tap

KIT #5404 PARTS LIST

REF. PART
NO. NO. QTY. DESCRIPTION

30. 04594 - EPDM Black Tubing

31. 05561 1 Solenoid Valve

32. 09153 1 Master Cylinder Gasket (not shown)

33. 10373 1 Brass Fitting Str. .2 HB x 10-32 NF

34. 10374 2 Crimp Clamp

35. 10375 1 Straight Nipple 1/8 MPT x 1/8 MPT

36. 10376 1 Brass Elbow 1/8 MPT x .2 HB

Note: -?? = -30 Black -91 Yellow Chromate

-95 Plated -97 Primed Red

Indicate color when ordering parts

Please order replacement parts by PART NO. and DESCRIPTION

Page 10

15

15

20

22

19

19

36

34

30

OUTER CASE OPTIONS AND AVAILABLE HITCH CONFIGURATIONS

37 38 39

40 41 42

45

54

48

47

43

43

44

56

44

54

RATED AT 8000#RATED AT 8000#

56

57

50

RATED AT 6000#

WARNING: TO AVOID PERSONAL INJURY OR

!

PROPERTY DAMAGE, OBSERVE THE FOLLOWING
INSTRUCTIONS:

The weight rating of the coupler is dependent on the
correct bolts being used. You must use the bolts
provided with the product. If you are missing bolts,
refer to your Operatorís Manual and obtain replace­ments from Demco, or use the exact size, grade,
and number of bolts as specified. Using the wrong
size, grade, or number of bolts will reduce the weight
rating of the coupler and could cause separation of
your towing equipment from the towing vehicle. If
you have questions about the correct bolts for your
application call Demco at any of the following tele­phone numbers:

[phone]
[phone]
1-800-543-3626
FAX: [phone]

Note: -?? = -30 Black -91 Yellow Chromate

-95 Plated -97 Primed Red

Please order replacement parts by PART NO. and

DESCRIPTION and COLOR.

46

56

55

54

51

52

2  RATED AT 7000#

2 -5/16 R AT ED AT 8000#

58

54

56

54

53

2  RATED AT 7000#

2 -5/16 R AT ED A T 8000#

54

56

49

59

54

54

2 -5/16 R AT ED A T 8000# 2 -5/16 R ATE D A T 8000#

PARTS LIST

REF.

NO. PART NO. QTY. DESCRIPTION

37. 11101-?? 1 Outer Case w/ no mounts

38. 11171-?? 1 Outer Case w/ plate

39. 11163-?? 1 Outer Case w/ 50  mount

40. 11168-?? 1 Outer Case w/ 3 hole mount

41. 11170-?? 1 Outer Case w/ universal holes

42. 11169-?? 1 Outer Case w/ 2 hole mount

43. 02587 2 5/8"-11UNC Nylon Insert Lock Nut

44. 02434 2 5/8"-11UNC x 4 1/2" Hex Head Bolt (Gr. 5)

45. 11076-?? 1 Channel Down Slider

46. 11077-?? 1 Channel Up Slider

47. 09557-?? 1 Pintle Ring (10 Ton Capacity)

48. 05593-?? 1 Clevis

49. 07678-?? 1 2-5/16" Lever Lock Bolt-On Coupler

50. 09430-?? 1 2î Lever Lock Coupler

51. 11070-?? 1 2-5/16" Bulldog Coupler Welded to Straight Slider Tube

- 11071-?? 1 2" Bulldog Coupler Welded to Straight Slider Tube

52. 11069-?? 1 2-5/16" Bulldog Coupler Welded to Drop Slider Tube

- 11072-?? 1 2" Bulldog Coupler Welded to Drop Slider Tube

53. 05557-?? 1 2-5/16" Bulldog Coupler Welded to Clevis Channel

- 05823-?? 1 2" Bulldog Coupler Welded to Clevis Channel

54. 04051 4 5/8"-11UNC x 1-1/2" Hex Head Bolt (Gr.5)

55. 11075-?? 1 Channel Centered Slider

56. 03730 4 5/8" Stover Locknut

57. 11081-?? 1 Slider w/ Flat Plate Mount

58. 11073-?? 1 Straight Slider w/ 2î Coupler

59. 11074-?? 1 Drop Tube Slider w/ 2-5/16î Coupler
Page 11

DETHMERS MFG. COMPANY

P.O. BOX 189

4010 320th St., BOYDEN, IA. 51234

PH: [phone] FAX: [phone]

TOLL FREE: 1-800-54DEMCO (1-800-543-3626)

www.demco-products.com

Page 12