Troubleshooting guide

ManualsBrandsBENDIX ManualsComputer equipmentEC-60 ABS-ATC ESP CONTROLLERS ADV

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Release time — Deﬁ ned as the time between initial movement

of the service brake pedal (suspended) or treadle (ﬂ oor

mounted) on release, to total disengagement of the mechanical

means, at the wheel end. With 95 psi delivered at the chamber,

FMVSS 121 speciﬁ cally requires that the period of time it takes

from the initial movement of the brake actuation means to the

pressure reaching ﬁ ve (5) psi in the chamber, be recorded.

Reservoir — A tank for compressed air. Typically, a

combination vehicle has several reservoirs: three in the tractor

and one per trailer. The tractor's supply air reservoir (formerly

"wet tank") receives air from the compressor and delivers it to

the primary and secondary air tanks in the tractor. A single

check valve, or equivalent device such as a pressure protection

valve, typically in each reservoir prevents total air loss in the

event of a leak.

Retarder — An auxiliary device such as engine brake, exhaust

brake, hydraulic retarder or electric retarder that slows the

vehicle by means other than friction-based braking.

Return springs — Springs attached to the brake shoes that

cause them to retract, upon release of the brake treadle.

Rotor — The braking surface for disc brake systems. Heavy

trucks typically have a cast iron rotor with a vented design. The

rotor can be either separate, or integral, to the hub.

RSC/RSP — Roll Stability Control/Roll Stability Program.

An all-axle ABS solution that helps reduce vehicle speed by

applying all vehicle brakes as needed, reducing the tendency

to roll over.

SAE — Society of Automotive Engineers (SAE) International

is a global association of engineers and related technical

experts in the aerospace, automotive and commercial-vehicle

industries. SAE International's core competencies are life-long

learning and voluntary consensus standards development.

SAS — Steering Angle Sensor.

S-Cam brake — Also known as Foundation Drum Brakes,

S-Cam is a type of brake where mechanically-induced rotation

of an S-shaped cam forces brake linings against the brake

drum.

Scored drum — A brake drum that results in excessive lining

wear because the friction surface has become grooved. Within

manufacturer's limits, severe scoring may be rectiﬁ ed by

machining, before replacing the linings.

Sensor clamping sleeve — A beryllium copper sleeve which

has ﬁ ngers cut into it. It is pressed between an ABS sensor

and mounting hole to hold the sensor in place.

Service brake — That portion of the brake system that can be

modulated — usually under the control of the operator's foot —

for normal stopping.

Slack adjuster — Sometimes called a brake adjuster, this

is a lever connecting the brake chamber push rod with the

foundation brake camshaft. It multiplies the push rod force by

the slack length to create a rotational force (torque) to rotate the

brake camshaft when the brake treadle is depressed. It also

provides a means of adjusting clearance between brake shoes

and the drum to compensate for lining wear. Some models

are automatic, while others require manual adjustment. Note:

Automatic slack adjusters should not be manually adjusted

except when performing a brake reline.

Speed sensor / ABS — An electromagnetic device that,

in conjunction with a rotating toothed wheel, transmits an

electrical signal, proportional to the wheel speed, to the ABS

Electronic Control Unit (ECU) .

Split-coefﬁ cient surface — Also called split-M ("split-Mu").

A road condition where one side of a lane has low friction and

the other has high friction (for example, when the left side of

the lane is icy, but the right side is dry). An ABS system with

individual wheel control will provide optimum stability and

stopping distance performance under these conditions.

Spring brake — Typically refers to a tandem-chamber brake

actuator that incorporates: (a) an air-applied service brake

chamber and (b) an air-release/spring-applied emergency

or parking brake chamber. In the event of a sudden air loss

(emergency mode) or activation of a dash-mounted parking

brake control, the spring brakes will apply. The spring brakes

remain applied until that chamber is recharged with air or the

spring is manually compressed or caged.

DISASSEMBLY OF A SPRING BRAKE

IS DANGEROUS. ONLY TRAINED MECHANICS SHOULD

ATTEMPT THE PROCEDURE.

The spring portion often is referred to as the piggyback. Spring

brakes generally come in two types: double-diaphragm or

piston-type.

Stopping distance — The distance traveled by a vehicle on a

road between the initial brake pedal movement and a complete

stop.

Stopping time — The time taken between the initial brake

pedal movement and a complete stop.

Stroke — Refers to a total distance traveled by a brake chamber

push rod, or slack adjuster arm, during brake application.

Brake chamber stroke is usually checked with 80-90 psi at the

service chamber as deﬁ ned by SAE.

Stored diagnostic trouble codes — A Diagnostic Trouble

Code (DTC) that occurred in the past. Useful for tracing

intermittent problems.

Glossary, continued