ABS Systems Flashcards
(42 cards)
On what date did ABS become mandatory on Heavy Duty Trucks and Trailers?
March 1st 1998
What are the four main benefits of ABS systems installed on a Heavy Duty Truck or Trailer?
Maintains control during braking, reduces stopping distances, saves on tire flat spotting & prevents wheel lockup.
If you are driving a pre ABS unit, how often could you pump the brakes in the event your wheels begin to lock up?
Humans can pump brakes about 3 times a second.
How many times can an ABS controlled system actuate the brakes to control wheel lockup in an ABS event?
Brake corrections are performed 100 times a second.
When a builder is designing a tandem axle trailer, what are the minimum requirements for ABS systems installed on it?
Trailers require two sensors, and one modulator.
On a system with a three axle design, what is the most effective setup of equipment that an ABS system can have?
6 sensors and 6 Modulators, one for each wheel end.
When speaking about ABS systems, what do Channels refer to?
Channels refer to the number of circuits that get modulated, or the number of modulators.
When a tandem axle unit that is equipped with Spring Suspension, which of the two drive axles offloads first, and where are the sensors located on this setup?
The front axle would offload first as the springs force the weight back, so the sensors are located on this axle.
When a tandem axle unit that is equipped with airbag style suspension, which of the two drive axles offload first, and where are the sensors located on this setup?
The rear axle would offload first and as such, the sensors are located on this axle.
On an ABS system specced as 4S / 3M, where would the sensors and modulators be located?
Two sensors and Two Modulators on steer axle
Two sensors and One Modulator on the drive tandems.
How many teeth on average are within an ABS tone ring?
Between 80-120 Teeth.
AC Voltage signals produced by ABS Wheel Speed Sensors produce two types, what are they? How are they measured?
Voltage - Measured in Amplitude
Frequency - Measured in Hertz
If the tone ring was to move away from the sensor or vice versa, what could the resulting effects be?
The voltage produced inside the wheel speed sensor would reduce. This way the ECU can tell the difference between a wheel slowing, or a wheel that is coming loose or worn wheel bearings.
Is the Modulator Valve normally open or normally closed?
Normally Open - to allow free flow of air until signalled.by the ABS ECU.
During a normal braking event, what positions are the solenoids in, inside the Modulator valve.
The supply solenoid is seated and de-energized
The exhaust solenoid is unseated and de-energized
During an ABS event, what positions are the solenoids iin, inside the modulator valve.
The supply solenoid is energized in the unseated posotion
The exhaust solenoid is energized in the seated position
When the ABS system instructs the modulator valve to hold, what position are the solenoids in?
The supply solenoid is energized in the unseated position
The exhaust solenoid is de-energized in the unseated position.
How fast are signals communicated by the ABS ECU?
Signals are transmitted in milliseconds.
If you have repaired an ABS system, cleared the codes and the light remains on, what should you do?
Drive the vehicle in a speed between 5-10km/h to have the light go off if no faults are present.
On which date did it become CVIP requirement to have an ABS light located on the left corner of a trailer?
March 1st 1998.
On which date did it become requirement to install a trailer ABS light in the cab for operators to see.
March 1st 2001
What is the one road condition that may increase the stopping distance while using ABS braking?
Loose dirt/gravel/sand.
If operators change shifts, and the unit was left running. The next operator takes over and notices that the ABS light is flashing on and off, what causes this?
The Off-Road feature has been enabled, and was not disabled after use.
If an operator is using a Pre-1998 trailer, and complains of the ABS light coming on during braking, what could this be?
The ABS system is powering up and self checking itself, as it gets its power source from the brake light pin on the trailer cord.
