Komatsu D20P-6A to D21A-7 specifications

Distinguish the D20 clutch pedal from the D21 inching system

Komatsu's dash-7 operator manual gives separate operating chapters for the D20 and D21. On the covered D20, the main-clutch pedal disconnects engine drive for starting, stopping and selecting a gear. The D21 has an inching pedal and a combined steering, direction and speed lever. Similar engine output in this comparison does not mean the operator uses the same travel controls.

The D20 instructions require stopping before a gear change. The D21 chapter describes changes of speed while travelling, while direction changes still require reducing engine speed. An unfamiliar operator should identify the exact arrangement before treating a difficult shift as a failed transmission.

The D21 lever also separates gradual steering from a pivot: initial side movement releases a steering clutch; further movement applies its brake. A demonstration that shows only a broad turn has not checked the same action as a pivot. Keep operation on suitable ground and follow the applicable manual's safety procedure.

D20P-6A hydraulic capacity is not the tank's physical volume

The dash-6 shop-manual extract identifies separate hydraulic piping for the angle-and-tilt blade arrangement and the straight-tilt P, PL and PLL machines. Its D20P-6A circuit drawing follows the engine-driven implement pump through the valve to lift, angle and tilt cylinders. A hydraulic complaint needs the fitted blade system identified before a test point is selected.

That extract distinguishes the total hydraulic-tank volume from the amount of oil it contains in service. Those are different definitions, so a capacity entry should not be used as a refill instruction without the matching procedure. It also separates work-equipment drift testing from pressure testing; a blade that drifts down has not, by that observation alone, established a worn implement pump.

PL and PLL track geometry belongs in the purchase decision

The retained tables distinguish track length, shoe width and roller count across P, PL and PLL. Those figures are useful for identifying the undercarriage being offered, even where several columns share the same gross engine rating. Check the fitted track assembly against that column before comparing transport space or ordering wear parts.

The dash-6 operation manual also distinguishes its D21A/P/PL and D21P-6A travel controls from D21E-6 and D21P-6B. The latter arrangement has a different gear schedule. A seller's description of a D21 is therefore insufficient to transfer every specification or operating instruction across this family.

The original engine, blade and transmission rows stay attached to each named version.