Tie Down 750E User Manual

Model 750E

Brake Actuator

Installation Instructions and Service Manual

Model 750E - 7,500 lbs. Capacity

Part #70521 Disc Brake
Part #70522 Drum Brake

Table of Contents Page

Actuator Installation Instructions 2
Hitching the Trailer 3-4
Vehicle Wiring - Free Backing Brake Solenoid 4
Actuator Maintenance 4
Warnings 5-6
Bleeding Instructions 7-8
Part Diagrams and Replacement Parts 9-12
Limited Warranty 13-14

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IMPORTANT: READ AND UNDERSTAND THE ENTIRE INSTRUCTION/ASSEMBLY
PROCEDURE BEFORE INSTALLING YOUR BRAKES AND ACTUATOR.

The Model 750E 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.
Be sure to comply with regulations for brakes in your state. 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. The Model 750E Actuator is
completely assembled and ready to bolt into place, if not all ready installed. Manufactured
for tongue sizes: 3”x 3”, 3”x 4” & 3”x 5”.

1. 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 than
1-1/2 times trailer G.V.W.R.

2. 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.

3. Use only DOT-3 heavy-duty brake fluid in the Model 750E actuator. Use a pressure
type brake bleeder to bleed brakes. (This type of brake bleeder is available at your
local automotive jobber.) Follow manufacturer’s directions. Or, manually bleed the
brakes using a heavy-duty flat blade screwdriver inserted in the hole provided on
top of the actuator near the front. Insert the screwdriver and use a pumping action
to activate the master cylinder in order to bleed the brakes.
See page 7 for more details.

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 a loose end of hose from the bleeder valve submerged in a glass
container of brake fluid to observe bubbling (hose must be submerged into clean
brake fluid to keep air from traveling back into the brake cylinder). Loosen the
bleeder screw located in the wheel cylinder one turn, the system is now open to the
atmosphere. 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. 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.

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4. Check with your state motor vehicle department for laws concerning minimum
trailer brake requirements. Some states may require brakes on all axles.

5. 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.

6. When 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. Road test again to make sure
brakes work properly.

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

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).

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. Model 750E will accept 2” or 50mm trailer hitch balls 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. Connect safety cables or chains using crossed pattern under tongue, or follow
trailer manufacturer’s directions.

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

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

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,
see page 8.

7. 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.

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DANGER: Tongue weight beyond rating limits will interfere with performance of
actuator, and braking system, and the tow vehicle.

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. For trailer movement when brakes are not required,
place the safety pin in the hole on the side of the actuator housing to block
movement of the actuator.
DANGER: 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.

Directions Vehicle Wiring - Brake Solenoid

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.

Maintenance

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 inch 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.

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