INSTALLATION INSTRUCTIONS

Dexter DX7.5 (Formerly Model 750E) Brake Actuator
#

TDE Part #

DX Part #

70519K Disc

K68-525-20

70519KD Drum

K68-525-00

1B

11286

054-240-00

Disc Brake Solenoid - used with
Disc Brake Actuators

2

70412

068-563-00

Latch Kit Assembly, with Drop-NGo™ Coupler,(for serial numbers
17927 and above)

1A

3

50317

068-738-10

4

50301

074-477-00

Safety Cable with stainless steel
pin - Includes mounting screw

70462K

5
1

Brake Master Cylinder Kit: master
cylinder and cap, 4 mounting
screws with washers, 2 rollers with
matching nuts and bolts

Emergency Stop Cable (E-stop/
Breakaway)

5

1&6

Description

K68-524-00

Actuator Covers, Includes: front
and rear cover plates and 4
mounting screws

6

48986A

068-572-00

Master Cylinder Fill Cap with
internal bladder, 2.25” Opening
(E-Models)

7

48844

046-259-00

Safety Spring with two mounting
screws

7

5

4

1A
1

1
2

IMPORTANT: READ AND UNDERSTAND THE ENTIRE
INSTRUCTION/ASSEMBLY PROCEDURE BEFORE INSTALLATION.

2.

The DX7.5 works by the “surge” or “push” of the trailer toward the tow
vehicle. This automatically synchronizes the trailer brakes with the tow
vehicle axle brakes. When the trailer pushes against the tow vehicle, the
actuator telescopes together and applies the force to the master cylinder,
supplying hydraulic pressure to the brakes. The built in dampening shock
absorber retards the telescoping shock against the hitch ball.

!

CAUTION

• DO NOT REUSE BRAKE FLUID. Always use fresh DOT 3 fluid
from a fresh container. Failure to maintain proper levels of
fluid in the reservoir will cause brake failure.
• ONLY USE DOT 3 or 4 brake fluid. DO NOT USE OF DOT 5 BRAKE
FLUID. DOT 5 brake fluid will cause damage to internal parts
that can result in loss of brake power.

CAUTION

Read your vehicle’s owner manual on towing capacity and other towing
recommendations before installing brakes or this actuator. The DX7.5
Actuator is completely assembled and ready to bolt into place, if not
already installed. Manufactured for tongue sizes: 3”x 3”, 3”x 4” & 3”x 5”.
Bolt the actuator to the tongue-using grade 5 bolts 1/2 inch in
diameter, 4 inches long. Lightweight tongues, less than 11 gauge,
require spacer tubes inside the tongue for reinforcement. Attachment
strength should equal or exceed 1-1/2 times trailer G.V.W.R.

©2019 Dexter Axle Company | www.dexteraxle.com

Hydraulic brake lines should be installed on the trailer as described
in the installation manual supplied with the brakes. Note: Some disc
brakes require the use of flexible brake lines at the connection point
on the brake caliper. Follow brake manufacturer instructions.

!

Brake laws sometimes are minimum standards and you may
wish to add additional brakes to your trailer. Read your tow
vehicles owner’s manual on towing capacity and other towing
recommendations before installing brakes or this actuator.

1.

3

5

-1-

3.

Use a pressure type brake bleeder to bleed brakes following
manufacturer’s directions. Or, manually bleed the brakes
following the instructions on page 3. Check with your state motor
vehicle department for laws concerning minimum trailer brake
requirements. Some states may require brakes on all axles.

4.

Road test trailer a short distance to activate the actuator several
times. Check fluid level again. Remember, low brake fluid levels will
result in hitch ball knocking.

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!

CAUTION

!

AVOID sharp turns, which can cause the actuator to bind or
jackknife against the tow vehicle or cause a bend in the tongue.
Either can damage the actuator causing brake failure. AVOID
towing trailer across large bumps or dips that may over stress
the connection between the trailer and tow vehicle, as this could
result in damage to the actuator.

CAUTION

Never allow the coupler latch safety pin to remain in the reverse
lockout position hole. After reverse maneuvering, always insert
coupler latch safety pin back into coupler latch. FAILURE TO
REMOVE SAFETY PIN FROM REVERSE LOCK OUT POSITION HOLE
WILL PREVENT FORWARD MOVEMENT BREAKING WHICH CAN
RESULT IN SERIOUS PROPERTY DAMAGE, INJURY OR DEATH.

RATED CAPACITY: Maximum Actuator Capacity: 7500 lbs. Gross
Load, 750 lbs. Maximum Tongue Load.

4.

Connect actuator breakaway cable S-hook to the tow vehicle only. Do
not connect S-hook to the safety cables or chains.

The actual in-service rating is limited to that of the ball and hitch being
used or the trailer manufacturer’s G.V.W.R. shown on the certification
label, whichever is lower (Note: G.V.W.R. is the Gross Vehicle Weight Rating
which includes the trailer and the load weight as a Total Gross Weight).

5.

The breakaway system is designed to only operate after the trailer
detaches from the tow vehicle and the safety chains have failed. Do
not use the breakaway as a parking brake.

6.

If the breakaway is accidentally applied, insert a flat bladed
screwdriver into the spring clip on the side of the actuator and pry
sideways pressure to release.

!

CAUTION

A minimum of 5% tongue weight and a maximum 10% tongue weight
of the trailer G.V.W.R must be located on the hitch ball. The Trailer
tongue should be parallel to the ground. Too much weight can cause
premature brake actuation and loss of control of the towing vehicle.
Too little tongue weight can cause the trailer to fishtail, resulting
in loss of control of the tow vehicle and trailer (total trailer weight
G.V.W.R. includes weight of the trailer plus load).

!
•
•

Hitching The Trailer
1.

The vehicle, towing hitch and ball must have a rating equal to or
greater than trailer G.V.W.R..

2.

DX7.5 will accept 2” ball only. Trailer balls larger than 2.00” (50mm)
or out of round will not fit the coupler or may result in coupler failure.
Balls smaller than 1.95” can cause shock loading and sudden
disconnection. Make certain ball latch is in correct position to retain
the hitch ball. Push latch until safety latch engages plate below latch.
Insert safety pin into forward hole as a safety lock for the hitch ball
coupler prior to towing. Do not tow trailer if coupler is damaged.

!
•

•

3.

•

Any control devices that restrict operation of the actuator cannot be
used. This includes certain sway control devices. The actuator must be
free to telescope in response to braking requirements.

8.

Equalizing or weight distributing hitches may be used, that are
designed to use with surge brake actuators, allow six to eight inches
free chain length.

!

CAUTION

Failure to remove pin will also prevent forward braking. Pin must
be in the lower, forward hole as a safety lock for the hitch ball
coupler latch when towing at all times.
9.

The actuator is designed for use with Free-Backing trailer brakes.
To block braking action, (in order to back up) with other types of
brakes including disc brakes, use an electric solenoid. Place the
safety pin in the hole on the side of the actuator housing to block
movement of the actuator for reverse movement without brakes.

Directions Vehicle Wiring - Brake Solenoid

Connect safety cables or chains using crossed pattern under tongue,
or follow trailer manufacturer’s directions.

©2019 Dexter Axle Company | www.dexteraxle.com

The breakaway system is not designed to operate if the
trailer does not separate completely from the tow vehicle, or
if the tongue goes under the rear of the tow vehicle.
In the event that the breakaway system is used, check all
system components for proper working order. Replace any
damaged parts with genuine Dexter parts only.
When resetting the breakaway system keep hands and fingers
clear as you re-set the mechanism, hydraulic pressure held in
the system may cause the assembly to snap back suddenly.

7.

CAUTION

Failure to install the hitch pin before towing can result in
accidental opening of the coupler hitch latch which can lead to
the trailer coming off of the hitch ball causing serious damage,
injury or death. If pin will not fit into the front lower hole, the
coupler is not attached properly. Reset coupler on hitch ball.
A loose fit between the coupler and hitch ball can cause the
actuator and hitch ball to separate, causing serious damage,
injury or death. Check coupler every time prior to towing and
at each stop on long trips. Always make certain that coupler
latch safety pin is securely installed into coupler latch.

CAUTION

-2-

1.

Disconnect trailer hitch and any wiring connectors from the vehicle.

2.

Connect a 14 gauge wire to the backup (reverse) light wire of the
vehicle. This wire should be of sufficient length to attach to the
existing vehicle/trailer wire receptacle. The end of this wire will require
a female end that will match the solenoid male connector wire. Your
vehicle may have a 5 wire connection for this purpose.

3.

For ease of use, tape or band the end of the reverse light wire to the
vehicle’s trailer electrical connector.
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5.

Maintenance

!

CAUTION

1B

The exterior of the actuator and brakes should always be rinsed with
fresh water after use in corrosive conditions. Before storing trailer,
clean brakes and repack the bearings. Failure to properly maintain
the actuator could cause serious damage, injury or death.
1.

Always check the brake fluid reservoir before using trailer. Make sure
it is at least half full. If not, re-fill to ³⁄₈” below the top of the reservoir
with DOT 3 brake fluid. Do not use DOT 5 brake fluid. Check for leaks
and repair as required. Never reuse brake fluid.

2.

To extend coupler and ball life, coat both with a thin coating of grease.
This will also eliminate squeaking. Wipe clean and renew film each
time trailer is used.

3.

Examine the actuator for bent parts or wear each time the trailer is
used. Replace parts as necessary.

4.

There are no user adjustments on the actuator.

5.

Actuator travel (shown by coupler roller path) over one inch indicates
a need to adjust the brakes or add fluid to the reservoir or a need
to bleed the brakes and check connections for leaks. Adjust per
instructions found in brake installation manual. In general, back-off
adjusters on drum brakes from locked position, as required. Adjust
Free-Backing brakes by rotating in forward direction only. Failure
to adjust may result in loss of braking. Disc brakes do not require
adjustment, check for pad wear.

Bleeding Instructions
1.

2B

To bleed master cylinder and
brakes, install bleeder hose on
first wheel cylinder to be bled;
if tandem axle trailer, bleed
closest axle first, and the closest
brake on that axle first. Use
aFRONT
loose end of hose from the
FRONT
bleeder valve submerged in a
FRONTcontainer of brake fluid to
FRONT
glass
observe bubbling (hose must be submerged into clean brake fluid to
keep air from traveling back into the brake cylinder).
Pump master cylinder, keeping pressure, using a flat tip screwdriver
(1A). Crack bleeder value open and tighten. Repeat until there are no
more air bubbles.

3.

The screwdriver should be at the lowest angle possible to the
actuator so that it slides in front of the e-stop bracket (See 1B).

4.

Screwdriver tip MUST BE IN FRONT of the e-stop bracket and NOT
in the slot on the e-stop bracket (See 2A).

©2019 Dexter Axle Company | www.dexteraxle.com

6.

The bleeding operation for that brake is complete when bubbling
stops. Be sure to tighten bleeder screw securely. Each wheel
cylinder must be bleed until all air is out of the lines. Replenish the
brake fluid during the bleeding process so the level does not fall
below half full level in the master cylinder reservoir.

7.

When bleeding and testing is completed, make sure master
cylinder is filled to ³⁄₈” below the top of the reservoir and filler cap
is securely in place.

Emergency Button Stop

Bleeding
Access Port

2.

Push the screwdriver forward and back to pump the master
cylinder. (See 2B).

Shown in normal
operating position

If button stop cable
is showing DO
NOT TOW TRAILER.
Release emergency
stop cable by prying
spring out with a
flat blade screw
driver.

-3-

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2019.10 | 08164-2