Contents

Introduction

Purpose, device and principle of operation of the gearbox

• Main gearbox
• Synchronizers
• Gearshift mechanism
• Shift control of the main gearbox
• Demultiplier
• Demultiplier design
• The device and operation of the demultiplier synchronizer
• Demultiplier control
• Power flows
• Gearbox lubrication

Transmission operation

Maintenance

• Daily maintenance
• Break-in maintenance
• First maintenance
• Second maintenance

Possible malfunctions of the gearbox with their solutions

Disassembly and assembly of gearbox type YaMZ-239

• Gearbox disassembly procedure
• Dismantling the secondary shaft
• Output shaft assembly
• Dismantling the layshaft
• Assembly of intermediate shaft
• Disassembly and assembly of the demultiplier

Troubleshooting parts gearbox YaMZ-239

• General technical requirements for troubleshooting gears and shafts
• Troubleshooting parts before assembly

Gearbox assembly

Features of adjusting the tapered bearings of the main gearbox type YaMZ-239

• Adjusting the relative position of the primary and secondary shafts
• Preparing the location of the intermediate and secondary shafts in the crankcase
• Adjusting the intermediate shaft rear bearing
• Rear output shaft bearing adjustment
• Adjusting the intermediate shaft front bearing
• Input shaft bearing adjustment

Running in the gearbox after assembly

• General requirements for running in gearboxes
• Basic requirements for a gearbox break-in test bench
• Switchability test
• Checking the demultiplier synchronizer
• Checking the automatic gear lock
• Checking gearboxes for leaks
• Requirements for the appearance of gearbox parts after running in

Gearbox acceptance rules

Packing, transporting and storing gearboxes