Deere 120 excavator: arm, tracks and pump circuits

The original 120 excavator's arm, tracks and pump circuits

Deere identifies the original 120's engine as a four-cylinder 4045T, with 4.5 litres of displacement. A six-cylinder engine entry, moldboard dimensions and all-wheel-drive grader figures do not describe this excavator. Those earlier mixed records are retained below with rejected-attribution labels.

They should not be used to order engine parts or establish this machine's transport size.

The hydraulic specification distinguishes two main piston pumps from a separate gear-type pilot pump. Each main pump has its own stated maximum flow. Quoting the single-pump value as the complete installation misses the second pump; treating the pilot flow as attachment supply makes a different mistake.

Deere also lists separate operating pressures for implements, travel and swing. The swing figure is lower than the implement figure, so a pressure measurement needs its circuit identified before it can be judged.

Two arms appear in the factory working-range chart. The shorter arm gives greater crowd force with the reference bucket; the longer arm adds excavation reach and depth. Both share the same listed bucket digging force for that bucket.

Transport height has another qualification: the long arm is pinned in its shipping position for the stated dimension. A machine parked with its linkage in another position cannot be assumed to match that height.

Track options change the stated weight and use restrictions. Deere lists narrow rubber tracks separately from the two steel-shoe widths, and explicitly excludes the rubber option from rocky conditions and side-slope work. The wider steel shoes reduce published average ground pressure, but also increase width and operating weight.

Each lifting chart names the arm and shoe combination. A convenient headline operating weight cannot select the chart by itself.

The attachment list separates fitted functions from preparation options. Reduced drift for boom lowering and arm retraction is standard in this publication, while auxiliary lines, auxiliary pilot controls, a load-lowering device and a control-pattern selector are optional. A thumb installation therefore needs more confirmation than finding a joystick button.

Bucket fit also has a small but useful distinction: the adjustable side-clearance bushing applies to the listed buckets except the ditching bucket. Deere offers different teeth and side cutters, which alter the actual attachment being measured.