Specifications

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DEMCO MODEL DA91 BRAKE ACTUATOR
• 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.
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.
WARNING
WARNING
SPECIALNOTE–WHENPRESSUREBLEEDINGBRAKESITISSTILLNECESSARYTOSHORT
STROKETHEMASTERCYLINDERSEVERALTIMESTOELIMINATETRAPPEDAIRBUBBLES.
Elevate tongue on trailer 4-6 inches
Refer to actuator parts breakdown page to locate referenced part numbers associated with procedures below:
Visually inspect actuator to ensure the inner slide is fully extended. This can be verified by making sure the black
copolymer slides (#19,#20,#21) are flush with leading edge of outer case.
*Failure to perform this function will prevent proper and complete bleeding of system*
Loosen or remove two 5/16” bolts (#13) that hold the lever guide and flat emergency lever spring (#12). •
Remove master cylinder fill cap (#17).
Usingshortstrokes,pullforwardonemergencylever(#16),pumpingmastercylinderuntilbrakeuidinmaster•
cylinder reservoir (#21)stops bubbling.
Attach a bleeder hose to a bleeder valve on one of the wheels (starting at wheel farthest from master cylinder ) •
and submerge other end into a transparent container partially filled with brake fluid to prevent possible splash-
ing from container.
Loosen bleeder valve one turn and while watching fluid in container, use emergency lever (#16) to pump fluid •
as long as bubbles continue to leave submerged hose. When bubbles stop, close bleeder valve, move to next
wheel and repeat until all brakes are bled. ( Note: Check master cylinder often (every 4-5 strokes) and refill
above half full as needed )
Refill master cylinder and securely attach cap (#17). Reinstall emergency lever spring, lever guide, lock wash-•
ers and 5/16” hex head bolts. When tightening the bolts, make sure the lever moves freely in the groove in the
guide.
Test brakes by pulling emergency lever (#11) forward until it locks into position. Lever will be pointing
approximately straight up. Attempt to rotate wheels in a forward direction. If any wheel rotates, brakes
assemblies must be adjusted.
Jackuptrailerandsecureonadequatecapacityjackstands.Followtrailermanufacturer’srecommendationsfor
lifting and supporting the unit. Make sure the wheel and drum rotates freely.
Remove the adjusting hole cover from the adjusting slot on the bottom of the brake backing plate.
With a screwdriver or standard adjusting tool, rotate the star wheel of the adjuster assembly to expand the brake
shoes. Adjust the brake shoes out until the pressure of the linings against the drum makes the wheel very difficult
to turn.
Back off the adjuster wheel 15-20 clicks. The wheel should turn freely with a possible, slight lining drag.
Replace the adjusting hole cover and lower the wheel to the ground. Repeat the above procedure on all brakes.
For best results, the brakes should all be set at the same clearance.
*Retest the brakes by locking the emergency lever on and attempt to rotate tires in a forward direction, if
any wheel turns there might be trapped air in the system yet.