DIFFERENTIAL RIGHT ANGLE GEARBOX

TM 9-2520-238-34

EQUIPMENT DESCRIPTION AND DATA -- Continued

0002 00

DIFFERENTIAL RIGHT ANGLE GEARBOX. A splined propeller shaft couples the right angle gearbox, through a universal

joint, to the carrier transmission output shaft. The splined shaft drives a matched spiral bevel gear set consisting of an input

shaft gear and an output bevel gear bolted to a shouldered shaft. The input shaft gear is mounted in roller bearings, and the

output bevel gear is mounted in ball bearings. The gears and bearings are adjusted by inserting or removing laminated shims.

Steering Control Differential Cutaway View

STEERING UNIT ASSEMBLY. The steering unit assembly consists of two planetary gear trains, a common carrier, and two

brake drums. Brake drum and control flange assemblies are rigidly coupled by a differential spider to form the carrier. Each

of the two gear trains consists of a brake drum hub with integral gear, three external spur gears, three spur gearshafts, and

steering spur gear. The external gears are fixed to their respective gearshafts and mesh with the integral hub which is bolted to

the hub brake drum, and the gearshafts mesh with the steering gear. The gearshafts of both gear trains are positioned in

groups of three, with the opposite gearshafts of each group meshing. The brake drums provide differential control.

BRAKE SHOE ASSEMBLY. Each brake shoe assembly consists of three brake shoes with replaceable brake friction linings.

Each set of brake shoes is held together by pins. They are of the contracting type arranged around the outside of the brake

drums. When the right or left brake control lever is pulled, the torque action of the steering brake shaft contracts the diameter

of the corresponding set of brake shoes and slows the rotation of that brake drum. When the brake control lever is released, a

spring enlarges the diameter of the set of brake shoes allowing the brake drum to increase speed.

OUTPUT SHAFT ASSEMBLY. The splines of the left or right output shaft mate with a left or right steering gear of the steering

unit assembly. Each shaft is ball bearing mounted, with bearings pressed on the shaft. The left output support is fixed to the

right angle gearbox. The right output support is fixed to the differential housing.

0002 00-7