Komatsu D31E/S/Q-20: blade, shovel and serial differences

D31E blade equipment versus D31S and D31Q shovel fronts

The three D31 names in this comparison do not identify interchangeable dozer arrangements. Komatsu's shop manual gives blade specifications for the D31E-20, but its D31S-20 and D31Q-20 sections describe bucket equipment and a dozer-shovel hydraulic circuit. Their loader arms, bucket lift cylinders and bucket dump linkage have separate component entries.

The bucket breakout and tipping figures below belong to those shovel fronts.

Serial ranges divide the manual further. Its drawings separate D31S and D31Q machines through serial 41183 from the later group beginning at 41184. The D31E drawings and specifications use another break, at 42714.

An engine or dimensional entry found on a neighboring manual page must therefore be matched to both the model and that page's serial heading. A shared dash number does not establish one engine arrangement throughout production.

Track width is a concrete difference between the two bucket-equipped models. In the later manual schedule, the D31S uses 330-millimetre shoes and the D31Q uses 600-millimetre shoes. Both lists contain thirty-seven shoes per side.

That wider footprint comes with its own frame and bucket dimensions; it cannot be described as merely fitting a wider blade to the D31E. The original comparison's width, pressure and bucket records stay alongside their named model.

Hydroshift engagement also has a specific explanation. The transmission's modulating valve controls how clutch pressure rises after a gear selection. Komatsu separates the time taken to fill the clutch circuit from the subsequent pressure buildup.

Together they form the modulation period. That description helps distinguish controlled engagement from a claim that every hesitation proves a bad torque converter. This manual's power path includes an engine damper and universal joint, and its Hydroshift transmission uses planetary gearing.

For a shovel hydraulic complaint, the relevant control valve has separate lift and dump spools. A suction valve serves the lift-cylinder head while the bucket lowers, preventing negative pressure there. A bucket that lowers poorly and a transmission that engages harshly therefore lead to different circuits in the same manual.

Preserve that distinction when recording a fault for a technician; the older steering accounts linked below remain accounts of their stated machines, not proof of a failure on every D31 variant.