Section II. DESCRIPTION AND DATA - TM-9-2520-249-34-P0006

TM 9-2520-249-34&P

1-5.

Reporting

Equipment

Improvement

1-2.

Maintenance Forms and Records

Maintenance forms and records which you are required

Recommendations (EIR).

to use are listed and explained in TM 38-750

EIR's will be prepared on DA Form 2407, Maintenance

Request. Instructions for preparing EIR's are provided

1-3.

Calibration

in TM 38-750, The Army Maintenance Management

Calibrations required are contained in this manual

System (TAMMS) EIR's should be mailed directly to:

Commander

US Army Tank-Automotive

1-4.

Quality Assurance/Quality Control (QA/QC)

Materiel Readiness Command

QA/QC will be in accordance with standards

ATTN: DRSTA-MCC

provided in this manual as well as those developed

Warren, MI 48090

by authorized maintenance units

1-6.

Repair Parts and Special Tools

Repair parts and special tools are listed in appendix B.

Section II. DESCRIPTION AND DATA

and counterclockwise rotations will be defined at the

1-7.

Description of Transmission Components

time the terms are used in the text.

a. The Allison XTG 250-1A transmission is an

NOTE

X-drive model which delivers power to left and right

sprocket drive shafts of a tracked vehicle The

Locational terms (front, rear, left, right) may

transmission, with principal exterior parts identified, is

not always agree with the same terms as

shown in figures 1-1 and 1-2.

established for the vehicle, due to variations

b. The transmission (refer to the cross

of transmission installation positions.

section, FO-1) consists primarily of a torque converter

with a lockup clutch; low-, intermediate- and high-range

1-9.

Detailed Description of Components

clutches; low- and intermediate-range planetary gear

The main components of the transmission are identified

sets; bevel gears and a cross shaft; left and right output,

in the cross-section view (FO-1). Chapter 2 covers, in

steer and reverse clutches; right and left steer and

detail, the description and operation of all components

reverse planetary gear sets; and left and right brakes,

and systems.

output shafts and output reduction gearing

c. Full powershifting under load, through four

1-10. Driving Instructions

forward and two reverse gear ratios, is a feature of the

Refer to TM 9-2350-230-20-1 for vehicle driving

transmission. Either of two methods of steer may be

instructions. (See appendix A.)

selected, depending upon whether the vehicle is being

operated on land or in the water The left and right

1-11. Transmission Oil

brakes, linked to a foot pedal, provide service braking

Oil may be considered as the life blood of the hydraulic

for the vehicle. A locking device in the brake linkage

transmission. The use of the proper oil, and attention to

permits the brakes to be used also for parking

keeping the oil clean, is of utmost importance. The

d. The transmission includes all hydraulic

proper oil level must be maintained in the transmission

components required for operation and control, except

to obtain maximum performance.

Check the oil

for an oil cooler which must be remotely mounted. All

regularly. Change oil and filters in accordance with LO

operator's controls are mechanically linked to the

9-2350-230-12 When changing or adding oil, use only

transmission.

Refer to chapter 2 for detailed

that specified (see oil specifications, table 1-1, para 1-

descriptions and explanations of all components.

12, following).

1-8.

Definition of Locational and Directional

1-12. Tabulated Data

Terms

Table 1-1, which follows, covers technical data,

The front of the transmission is the end which mounts

applicable to the XTG 250-1A transmission.

on the vehicle engine; the rear is opposite Left and right

are at the viewer's left and right when he is at the rear of

the transmission, and facing toward the front. Clockwise

1-2