Locating and Removing the Transmission Pump on a Caterpillar 950F Series II
The Caterpillar 950F Series II wheel loader is a mid-1990s production model equipped with a powershift transmission and a torque converter. The transmission system is hydraulically actuated, relying on a dedicated transmission pump to generate the necessary pressure for clutch engagement, lubrication, and torque converter operation. This pump is critical to the machine’s ability to shift gears and move under load.
The transmission pump is gear-driven and mounted externally on the transmission housing. It draws fluid from the transmission sump and supplies it to the control valve and torque converter. A failure in this pump can result in loss of drive, delayed shifting, or overheating.
Transmission Pump Location
On the 950F Series II, the transmission pump is typically located:
- On the lower right-hand side of the transmission housing
- Mounted directly to the torque converter housing or input gear case
- Driven by the torque converter gear train
To access the pump, the following components may need to be removed or repositioned:
- Belly pan or undercarriage guard
- Hydraulic lines connected to the pump inlet and outlet
- Electrical harnesses or brackets obstructing access
The pump is secured with several bolts and sealed with a gasket or O-ring. It may be necessary to drain the transmission fluid before removal to prevent spillage.
Removal Procedure
Steps to remove the transmission pump:
- Park the machine on level ground and engage the parking brake
- Disconnect the battery to prevent accidental starts
- Remove the belly pan to expose the transmission housing
- Drain the transmission fluid into a clean container
- Label and disconnect hydraulic lines from the pump
- Remove mounting bolts and gently pry the pump away from the housing
- Inspect the pump drive gear and mating surfaces for wear or scoring
- Clean the mounting surface and prepare for reinstallation or replacement
Common Symptoms of Pump Failure
Operators may notice the following signs of a failing transmission pump:
- Machine won’t move in forward or reverse
- Delayed or harsh gear shifts
- Transmission oil overheating
- Low transmission pressure warning
- Whining or grinding noise from the transmission area
In cold climates like Alaska, where one of the operators was based, pump failure may be accelerated by thickened oil or ice contamination. Using the correct viscosity fluid and warming the machine before operation can extend pump life.
Replacement and Rebuild Considerations
Replacement pumps are available from Caterpillar dealers and aftermarket suppliers. When sourcing a new pump:
- Verify the part number using the machine’s serial number
- Inspect the old pump for signs of cavitation, scoring, or broken gears
- Replace the gasket or O-ring to ensure a proper seal
- Flush the transmission system to remove debris or metal particles
Some operators choose to rebuild the pump if the housing and gears are intact. Rebuild kits typically include:
- Shaft seals
- Bearings
- Gaskets
- Pressure relief valve components
Field Case and Operator Insight
A retired quarry mechanic from New York noted that pump removal on the 950F is straightforward with the right tools and a clean workspace. He emphasized the importance of checking the suction screen and filter after pump failure, as debris can circulate and damage new components.
Another operator shared that a similar issue on a 966C was misdiagnosed as a clutch pack failure, when in fact the transmission pump had sheared its drive gear. A $400 pump replacement saved the machine from a costly teardown.
Final Thoughts
The transmission pump on a Caterpillar 950F Series II is a vital component that, while often overlooked, plays a central role in machine mobility. Understanding its location, removal procedure, and failure symptoms allows operators and mechanics to diagnose issues quickly and avoid unnecessary downtime. With proper maintenance and timely replacement, the 950F can continue to deliver reliable performance in even the harshest environments.
