HYDARULICS SYSTEM OVERVIEW AND DIAGRAMS
THIS WORK PACKAGE COVERS:
Hydraulics System Overview and Diagrams
The hydraulics system consists of the hydraulic reservoir, the main hydraulic pump assembly, the power take--off
(PTO) clutch, the auxiliary hydraulic pump, the main winch, the auxiliary winch, the hoist winch, a filter valve manifold,
the main and hoist winch directional control valves, the hydraulic control manifold assembly with all major hydraulic
controls, the spade lock, two spade cylinders, two boom cylinders, two stayline cylinders, the level winder, a spade
lock control valve, a boom shutoff valve, two boom limit valves, the refuel pump motor and controls, the impact
wrench with controls, may include a main winch power reduction manifold and related lines and connections.
In the main hydraulics system, oil is pumped from the hydraulic reservoir by a charge pump through the charge filter
to two variable displacement pumps: one for the spade, boom, and auxiliary winch; the other for the main winch and
hoist winch. The charge pump and variable displacement pumps make up the main hydraulic pump assembly and
are driven by main engine power. An electromagnetic PTO clutch is used to connect the main pump assembly to the
engine. When the hydraulic pump assembly is operating, pressures of 400 to 4400 psi are supplied to the hydraulic
components. All hydraulic components can be operated by main hydraulic pump pressures except the fuel transfer
pump and the impact wrench. Hydraulic oil is returned to the reservoir by way of a return filter and hydraulic oil cool-
The auxiliary hydraulic pump is driven by the auxiliary power unit (APU). The pump delivers 1600 psi and can oper-
ate all hydraulic components in a no load condition. The auxiliary hydraulic pump is also the only source of pressure
for operation of the fuel transfer pump and the impact wrench.
For the relationship of the various hydraulic components refer to FP23 through FP27.
The Enhanced Diagnostic System (EDS) aids the maintainer with hydraulic troubleshooting. The EDS consists of 32
hydraulic pressure transducers, five switches, eight wiring harnesses and a remote terminal unit which are perma-
nently mounted in the vehicle. The transducers and switches are mounted in the hydraulic system in places where the
maintainer would normally have to insert gauges to gather pressure data. The hydraulic pressure data gathered by
the transducers and switches is sent to the remote terminal (RT) unit where it is transmitted via a 1553 data bus to
the Solders Portable On--system Repair Tool (SPORT). The EDS software program running on the SPORT receives
the pressure data from the 1553 data bus and displays it for the maintainer in an easily readable graphical user inter-
face (GUI) that runs in a Microsoft Windows environment.