Hoist Circuit Operation - Komatsu 930E-2 Shop Manual

Note: Figure 2-1 illustrates the general location of the
hydraulic components on early production models.
Refer to Figure 2-2 through 2-5 for components in-
stalled on current production trucks.
The hoist, steering and brake circuits share a common
hydraulic tank (3, Figure 2-1). The tank is located on
the left side of the frame, forward of the rear wheels.
Service capacity of the tank is 250 gal. (947 l). Type C-4
hydraulic oil is recommended for use in the hydraulic
system.
NOTE: It is highly recommended that any hydraulic oil
to be used for filling or adding to the hydraulic system
is routed through a 3 micron filter device prior to use.
Oil used in the hoist, steering and brake circuits flows
from the bottom of the tank through 100 mesh wire
suction strainers.
Relieve pressure before disconnecting hydraulic
and other lines. Tighten all connections before
starting truck.
Hydraulic fluid escaping under pressure can have
sufficient force to enter a person's body by pene-
trating the skin and cause serious injury and pos-
sibly death if proper medical treatment by a
physician familiar with this injury is not received
immediately.
Always maintain complete cleanliness when open-
ing any hydraulic connection. Insure that all sys-
tem lines are capped while the component is
removed from the truck.
L2-2

Hoist Circuit Operation

Hydraulic oil from the tank (8, Figure 2-2) is supplied
to a gear type hoist circuit pump, rated at 246 GPM
(931 l/min.) @ 1900 RPM and 2500 psi (17.2 MPa). Oil
from the pump outlet port is directed to high pressure
filters (7) and then enters the hoist valve (4).
The hoist pump (and steering/brake pump) is driven by
a driveshaft (6) off the rear of the traction alternator.
The hoist valve directs oil flow to the hoist cylinders (1)
when the operator moves the body dump control lever.
The body dump lever is connected to the hoist pilot
valve located in the hydraulic components cabinet by
a flexible control cable. If the control lever is in the float
position, oil is returned to the hydraulic tank through
the Brake/Hoist Return Oil manifold (2, Figure 2-2) and
also flows through the disc brake circuit to cool the wet
disc brake system. Heat generated during service
brake application is removed by an oil-to-water heat
exchanger (1, Figure 2-5).
Hoist system pressure is limited to 2500 psi (17.2 MPa)
maximum pressure.
Hydraulic System L02028