TM-9-2320-283-13-P

0002-1

TM 9-2320-283-13&P

0002

OPERATOR AND FIELD MAINTENANCE

EQUIPMENT DESCRIPTION AND DATA

EQUIPMENT CHARACTERISTICS, CAPABILITIES, AND FEATURES

The ABS installed on the M915A1 tractor is provided to keep wheels from locking up during braking. ABS also

enables the operator to maintain steering control under heavy braking by preventing the tractor from skidding

sideways. In addition, the increased stability during braking resulting from ABS reduces the chances of a crash

and/or severity of impact in a crash.

ABS significantly improves safety and control for operators when braking in most on-road conditions and other

types of terrain. On high-traction surfaces such as concrete and asphalt, braking distances are minimized with

the ABS. However, in other types of terrain or conditions such as on gravel or in deep snow, ABS may increase

braking distances as a result of preventing wheel lock-up during braking. On very slippery surfaces such as sheet

ice, ABS may lose its effectiveness to prevent a skid because it becomes possible to lock multiple wheels at

once.

The ABS consists of four wheel speed sensors, four modulators, and an Electronic Control Unit (ECU) installed

on the existing brake circuit. The system performs a self-check automatically and warning indicator light alerts

operator to any malfunction should it occur. A test blink code switch allows the maintainer to troubleshoot ABS

without the use of hand-held or PC-based diagnostic tools. A diagnostic connector is also provided to enable the

use of remote diagnostic tools for troubleshooting.

LOCATION AND DESCRIPTION OF MAJOR COMPONENTS

This work package covers major components of the ABS.

WHEEL SENSOR – There are four identical wheel sensors each located on axle spindle and brake spider

housings of front axle and rear-rear axle. The wheel sensor remains stationary and is initially adjusted so that

it contacts the tone ring on wheel hub. The wheel sensor is an electrical component in the shape of a

cylinder with a power cable connected to ABS ECU via speed sensor harness.

WHEEL SENSOR

Figure 1 Wheel Sensor.

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