Brake Test Flashcards
Cut In psi
Not lower than 100 psi
Cut out psi
Compressor must shut down prior to 130 psi. Run engine at high idle to preform this test
Low-pressure warning psi
Between 55 - 75 psi
Applied leak test
Should not lose more than 3 psi in one minute
Static test (reservoir leak)
No more than 2 psi in one minute
Parking brake activation test
Emergency activation between 20-45psi
Rate of pressure build up
85psi up to 100psi within 45 sec
Push rod max travel distance
2in on 30in brake pod
Appropriate psi for s cam brake test.
90psi
Spring brake
parking brake, air is used to compressed a large spring. Once brake is pulled or air pressure is below 40psi the spring is released applying the brake.
Service brake
When brake pedal is applied compressed air fills the brake pod moving the diaphragm and the push rod
Brake sequence
Brake pedal applied - air fill brake pod- diaphragm moves push rod - push Rod moves slack adjuster- slack adjuster rotates cam shaft- cam shaft rotates S Cam - s cam moves cam roller forcing shoes to spread- shoes contact brake drum and stop wheel
Parking brake test.
Seatbelt on and parking brake set slowly pull against it in low gear
Service brake test
With normal air pressure pull forward slowly 5 mph and apply brake. Note any pulling to either side or delayed stopping action.
