Landoll Axle Trailer 455-48'

WARNING: Failure to replace faulty brake drums will result in an unreliable braking system, and may lead to an accident.

1. Clean and inspect the brake drums whenever relining the brakes. To be suitable for further service, the brake drum should pass the following checks.

a. The brake surface should be free of scoring, excessive heat checks and cracks.

b. The brake surface diameter should be within the maximum diameter cast or stamped on the drum.

c. The mounting holes and pilot must be round and true.

d. The mounting surface must be clean and flat.

2. It may be necessary to turn or resurface the braking surface to remove small heat checks or other surface defects resulting from normal use.

a. The maximum diameter cast into the back plate portion of the brake drum is the maximum diameter or discard diameter to which the brake drum may be turned or worn and still be usable. If any portion of the brake surface exceeds the maximum diameter it must be discarded. The maximum is .120 over the nominal new diameter unless stated otherwise on the casting. The maximum diameter cast into the brake drum supersedes all published information.

b. When resurfacing a drum, allow at least 0.040 inches under the maximum diameter for additional wear.

Chock all tractor and trailer wheels and drain the air system

Mark the brake chamber for proper air line port alignment for reassembly

CAGE THE POWER SPRING following the steps outlined in “Caging the Power Spring” on page 4-19

Disconnect the slack adjuster from the connecting rod by removing the clevis pin

Mark all air service lines for proper reinstallation and disconnect from the brake chamber

Remove the brake chamber from the axle brackets

Before adjusting, the vehicle must be empty with the kingpin at operating height and have air supplied to the trailer.

Disconnect linkage at all three control arms and raise the center axle control arm to the “up” position

Raise the trailer until a spacer block can be placed between axle tube and undercarriage frame

Lower the trailer by exhausting air from the air springs by moving the control arm to the “down” position until the axle tube is resting on the block

Return the control arms slowly to the center position

Insert wood locating pins into the adjusting block and bracket on the height control valves

Loosen the 1/4” adjusting lock nuts located on the adjusting blocks

Reconnect the linkages and torque to 24-48 inch lbs

Retighten the 1/4” adjusting lock nuts at the adjusting blocks to 24-48 in. lbs

Rotate the manual adjuster clockwise until brake shoes contact drum

Back off manual adjuster 1/2 turn (counterclockwise)

Manually uncage the spring brake

Fully apply and release the brakes several times to check for adequate clearance to all adjacent components

Measure the distance from air chamber to 1/2” pin

Apply brakes with 100-105 psi air pressure and remeasure distance to 1/2” pins

Calculate the stroke (difference of these two measurements)

The stroke (difference of these two measurements) must be less than 2 inches

Vehicle is empty with the kingpin at operating height and have air supplied to the trailer

Linkage at the control arm disconnected and control arm raised to the “up” position

Block placed between axle tube and undercarriage frame

Wood block positioned between the axle tube and frame according to table

Trailer lowered by exhausting air from the air springs by moving the control arm to the “down” position until the axle tube is resting on the block

Ride height checked and is correct

1/4” adjusting lock nut located on the adjusting block loosened, allowing the control arm to move approximately 1 inch

Adjusting block moved until holes align, then locating pin inserted

Control arm linkage aligned to the control arm lower bracket and 1/4” adjusting lock nut re-tightened to 2-4 ft. lbs