HP2 Tandem Pump

The HP2 Tandem Hydraulic Pump is a 12cc vertically integrated dual pump system that has independently controlled pump sections. The lower section controls the right side of the Mammoth, the upper section controls the left side. This is a closed loop, variable displacement pump with a 3.2cc Charge Pump and 2.5 quart integrated reservoir. There is also an internal 20 micron filter that is serviceable during the initial 50 hour break-in oil change and every 500 hours after.

There will be no internal service to the pump for the first 100 hours. Failed pumps will be sent to Parker for inspection. After 100 hours the pump can be serviced internally.

Maintenance Kits:

1. Gasket and Seal Kit
2. Oil and Oil Filter

Oil Expansion Tank

The Hydraulic Oil Expansion Tank is primarily used to allow for the expansion of hot oil during operation of the Mammoth 850. There is a cold fill stop on the tank, which will serve as an indicator line during any oil fill process. This allows approximately 1 quart of oil to be provided at all times in the tank.

When draining the oil, filling the oil, or purging air from the hydraulic system, you should have the cover removed from the expansion tank. The tank has two separate hoses to allow for oil fill to each section of the HP2 tandem pump.

Hydraulic Hoses

The hydraulic hose lines for the Mammoth 850 hydraulic system are Parker OEM products and have a 3,000 PSI rating. Take caution to always mark each hose prior to removal to ensure it is installed correctly. The drivelines on the Mammoth are configured in series for the left side and the right side.

Left Side: a hose from the pump’s top right port will lead to the front wheel motor, a second hose from the front wheel motor to the rear wheel motor, and a third return hose from the rear wheel motor back to the pump’s top right port.

Right Side: a hose from the pump’s bottom left port will lead to the front wheel motor, a second hose from the front wheel motor to the rear wheel motor, and a third hose from the rear wheel motor back to the pump’s top right port.

Drive Lines / Hoses

Parker DF Wheel Motor

The Parker DF Series 280cc Wheel Motors have 1.25" tapered output shafts and come with mounted brake hubs and spring-engaged brake levers. The brake system for these wheel motors is static, not dynamic, meaning that the Mammoth 850 should come to a complete stop prior to the Parking Brake being engaged. The wheel motors are designed by Parker for low-speed operation, which is why the Mammoth 850 travels up to 8 MPH in forward and 4 MPH in reverse.

The two wheel motors on the left side are connected in series as well as the two wheel motor on the right side. Together, this creates a four wheel drive system. Each wheel motor is serviceable after 100 hours of operation. In the event that a failed wheel motor comes to your dealership prior to the 100 hour threshold, it will need to be sent to Parker for analysis. Beyond 100 hours, a service seal kit is available for teardown and inspection.

Service Manual

Pump to Hose Fittings

The pump fittings are all O-ring style fittings, not 37-degree flare fittings. Three of them are 45-degree hydraulic elbow fittings (45-8-8), and the one bottom left fitting for the rear, right side wheel motor is a hydraulic swivel elbow fitting.

Prior to removal of any driveline, it is important to mark the hose-end-to-fitting connection for proper re-installation. You will need a 15/16" open-end wrench to remove the hoses from the fittings and a 15/16" crowsfoot to properly torque each fitting.