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