TM 5-3810-306-20
HYDRAULIC SYSTEM
General
Each hydraulic valve bank is tapped with a pressure test port for checking the relief valve settings. The pressure settings
can be checked by removing the appropriate test port plug and installing a flexible hose and pressure gauge.
The supply pressure and return circuit is made up of four (4) separate circuits which route oil from the two hydraulic pumps
to the directional control valves for the individual operating circuits. The supply pressure and return circuit consists of the
reservoir, hydraulic pumps, pump disconnects, oil cooler, oil filter, and an 11 port hydraulic swivel. The operating circuits
description and components begin with the circuit’s directional control valve.
The supply pressure and return circuit uses ports 7, 8, 9, and 10 for pump supply and the dual port 11 for return.
Hydraulic Reservoir
The reservoir, attached to the right side of the carrier frame, has a useable capacity of 165 U.S. gallons (624.52 liters).
The all-steel reservoir has an internally mounted full-flow filter and integral baffles that help cool the oil and prevent oil
foaming.
Oil flows through hoses from the back of the reservoir to each hydraulic pump. The return oil also flows to the back of the
reservoir, but on the opposite side of a baffle plate which acts to separate return and supply oil. Five return lines are
connected to the back of the reservoir, three of them go directly into the reservoir and the other two go directly into the filter
case inside the reservoir. The three lines that go directly into the reservoir are from the No. 1 port of the swivel and the
drain from the integrated outrigger valve, steering relief valve, steer flow divider, and hand pump.
A magnetized drain plug is located in the bottom of the reservoir to collect metal particles from the oil should the oil
become contaminated.
A sight gauge is located on the front of the reservoir to indicate oil level. A breather cap (vent) is located on the top of the
reservoir to allow air to enter or exhaust from the reservoir. It is most important that the breather be kept clean to prevent
damage to the reservoir. A large round access cover on the top of the reservoir provides access for cleaning. This
opening may also be used to fill the reservoir after it has been completely drained.
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