Multiquip DCA-600SSK -TRAILER BRAKES MAINTENANCE, Air Brake System, S-Cam Brakes

DCA-600SSK —TRAILER BRAKES MAINTENANCE

Brakes

Trailer brakes should be inspected the first 200 miles of operation. This will allow the brake shoes and drums to seat properly. After the first 200 mile interval, inspect the brakes every 3,000 miles. If driving over rough terrain, inspect the brakes more frequently.

Air Brake System

Air brakes use compressed air to make the brakes function. Air brakes are a good and safe way of stopping large and heavy vehicles. There are many components that make up an air-brake system, such as the air compressor, air compressor governor, air storage tanks and air tank drains. These components need to be maintained by qualified and trained technicians.

S-Cam Brakes

When the brake pedal is pushed, air is let into each brake chamber (Figure 76). Air Pressure pushes the rod out, moving the slack adjuster, thus twisting the brake cam shaft. This turns the s-cam (so called because it is shaped like the letter "S").

The s-cam forces the brake shoes away from one another and presses them against the inside of the brake drum.When the brake pedal has been released, the s-cam rotates back and a spring pulls the brake shoes away from the drum, letting the wheels roll freely.

Figure 76. Hydraulic Brake Components

Brake Drums (or discs), Linings, and Hoses

Brake drums or discs must not have cracks longer than one half the width of the friction area. Linings must not be loose, soaked with oil or grease or be dangerously thin. Mechanical parts must be in place, not broken or missing. Check that all air hoses connected to the brake chambers are not worn or cut due to rubbing.

Air Tank Drains	Air Leaks
Compressed air usually has some water in it which is bad	Always check for brake air leaks before towing the trailer.
for the air brake system. Water can freeze in cold weather	NEVER tow the trailer with an brake air leak problem. The
and thus cause brake failure. The water tends to collect in	possibility exists of brake failure.
the bottom of the air tank. Daily air tank drainage is required

to remove water from the air tank.
			Table 15. Air Brake Troubleshooting
		Symptom		Possible Cause	Solution
				Air Brake line broken or kinked?	Repair or replace.
		No Brakes		Worn lining?	Replace lining.
				Slack adjustment incorrect?	Adjust correctly.
				Brake lining glazed?	Reburnish or replace.
	Use Table 15 as a basic
				Trailer overloaded?	Correct weight.
	troubleshooting guide when	Weak Brakes or Brakes Pull to
NOTE				Brake drums scored or grooved?	Machine or replace.
		One Side
	brake problems occur.
				Tire pressure correct?	Inflate all tires equally.
				Tires unmatched on the same axle?	Match tires.
		Locking Brakes		Brake components loose, bent or broken?	Replace components.
				Brake drums out-of-round?	Replace.
				Brake lining glazed?	Replace brake lining.
		Noisy Brakes		Drums and lining glazed?	Replace brake lining and
					drum.
				Brake lining thickness incorrect or not	Install new shoes and linings.
		Dragging Brakes		adjusted correctly?
				Zerk fittings lubricated?	Lubricate zerk fittings.

PAGE 56 — DCA-600SSK — OPERATION AND PARTS MANUAL (STD) — REV. #7 (04/30/10)