MODEL LP850 ACTUATOR INSTALLATION INSTRUCTIONS
IMPORTANT: READ AND UNDERSTAND THE ENTIRE INSTRUCTION/
ASSEMBLY PROCEDURE BEFORE INSTALLING YOUR BRAKES AND ACTUATOR.
The Model LP850 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. A
knocking noise from the actuator during breaking could indicate low fluid level, check
immediately.
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 LP850 Actuator is completely assembled and ready bolt in place, if needed.
1. 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.
2. Use only DOT-3 heavy-duty hydraulic fluid in the Model LP850 actuator. Use a
pressure type brake bleeder to bleed brakes. (This type of brake bleeder is
available at your local automotive supplier.) Follow manufacturer’s directions. Or,
manually bleed the brakes using a heavy-duty flat blade screwdriver inserted in
the hole provided on the side of the actuator. Insert the screwdriver and use a
pumping action to activate the master cylinder in order to bleed the brakes.
See page 8 for more details.
To bleed master cylinder and brakes, the bleeder hose must be attached to the
highest (top) valve on the caliper, 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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