What Causes Poor Braking

If your brakes seem weak like they are out of adjustment and you have checked the brake adjustment, there are a few other things to check.

Inspect the air lines look for kinked lines, remove the air line from the service valve and check air pressure, there may be an air restriction. Drain the air from all of the air tanks and remove the drain valves, that way everything will drain out, water will reduce your air volume.

If a high volume of oil is drained from the air tanks, this may also affect your braking, the thick oil can restrict or block air passages in your foot valve and relay valves. Replace your air compressor as soon as possible, drain and flush your tanks many times, it will take a long time to get the oil out of the air system.

Inspect s-cam movement, sticky cams or bent components will reduce braking. Look at your brake drums, grooved drums will have reduced stopping power. Inspect your shoes, shoes covered in grease or gear oil will have reduced stopping power.

If the rod on your brake can face forward, remove the service side of the can, it could be packed full of sand and gravel and if you have been running in snow it will be full of snow and ice, which will cause little or no movement of the s-cam or brake rod.

Inspect the foot valve in the cab, sometimes the plunger or the pedal itself, will get sticky and not deliver the air to the valves. Look behind or under the pedal, make sure it’s not obstructed by a floor mat or something. Listen for air leaks, watch the pressure gauges for big pressure drops, fix any leaks.