Defines stab as brake till lock let off then brake till lock let off… Defines controlled as bake as hard as you can without locking.

2 inches

A long stroke Type 30 is designated Type 30LS, and has a maximum available stroke of three inches. In this diagram, the brakes have been applied and the brake linings have contacted the brake drum. The brake chamber has stroked less than half of its maximum stroke, indicating that the brake is in correct adjustment.

To make an emergency stop with air brakes, using the stab braking method, you should: A Pump the brake pedal rapidly and lightly. C Brake as hard as you can, get off the brakes when the wheels lock, get back on the brakes when the wheels start rolling again.

You must check that all shut-off valves are in the open position, except the ones at the back of the last trailer, which must be closed. Newer trailers have spring brakes just like trucks and truck tractors. However, converter dollies and trailers built before 1975 are not required to have spring brakes.

Controlled braking: 1) Can be used while you are turning sharply. 2) Involves locking the wheels for short periods of time….Escape ramps are:

1. Used to stop runaway vehicles.
2. Used to get out of a burning truck.
3. For combination vehicles only.

Supply Pressure Gauges All air-brake vehicles have a pressure gauge connected to the air tank. If the vehicle has a dual air brake system, there will be a gauge for each half of the system (or a single gauge with two needles). These gauges tell you how much pressure is in the air tanks.

What causes brake fade? Fading or reduction in braking effort occurs when the heated drums expand away from the brake linings. The brake linings also lose their effectiveness with overheating.

Cards

Air brakes

Air braking takes more time than hydraulic braking because air brakes: A Need to have airflow through the lines to work.

Spring brakes are usually used to meet these needs. When driving, powerful springs are held back by air pressure. If the air pressure is removed, the springs put on the brakes. A parking brake control in the cab allows the driver to let the air out of the spring brakes.

Heavy vehicles need larger gaps in traffic than cars. The best way to cross the traffic is to pull the vehicle partway across the road and block one lane while waiting for the other to clear. You are driving on a straight, level highway at 50 mph. There are no vehicles in front of you.

Blocking is used in the front, back, and/or sides of a piece of cargo to keep it from sliding. Blocking is shaped to fit snugly against cargo. It is secured to the cargo deck to prevent cargo movement. Bracing is also used to prevent movement of cargo.

Missing or broken leaves in any leaf spring. If 1/4 or more are missing, it will put the vehicle “out of service,” but any defect can be dangerous (Figure 2-3).

Why does your vehicle speed naturally increase on downgrades: Gravity. You are driving a heavy vehicle. You must exit a highway using an off ramp that curves downhill.

CDL 2.1