Komatsu 830E-AC Shop Manual page 786

HOIST COUNTERBALANCE VALVE
Preparation:
Note: The ports and valves referred to in the
following procedures
counterbalance manifold valve body.
1. With the engine shut down, the body resting on
the frame, the hoist valve in the FLOAT position
and hydraulic system pressure bled down,
loosen locknut on adjustment stem of needle
valve (9, Figure 10-9) on counterbalance mani-
fold (2). Turn adjustment stem fully clockwise.
2. Remove fitting from "PILOT VENT" port (8) on
counterbalance manifold. This port will remain
open to atmosphere during adjustment; do not
allow dirt to enter open port.
Note: It is suggested a clean SAE #4 (1/4") hydraulic
hose is installed in the open port and the hose
pointed downward.
3. Install a 35,000 kPa (5000 psi) gauge at test
port "TR" (7) on counterbalance manifold.
(Gauge will measure rod end pressure; the
pressure controlled by the counterbalance
valve.)
FIGURE 10-8. COUNTER BALANCE VALVE
1. Hoist Valve
2. Counterbalance Manifold
3. Power Down Test Port (TPD)
4. Counterbalance Valve (CBV)
5. Counterbalance Valve Test Port (TCBVP)
6. Power Up Test Port (TPU)
7. Test Port (TR)
8. Pilot Vent Port
L10-18
are labelled on the
Hydraulic Check-out Procedure
Counterbalance Valve Pressure Check Only:
1. Start the engine. At low idle, raise the body and
as it extends to the third stage, read the pres-
sure on the gauge connected to the "TR" port.
(All counterbalance valve pressures are read/
adjusted while hoist cylinders are in third stage.)
a. If pressure is 20 684 kPa (3000 psi) or
above, stop hoisting immediately.
Pressure is adjusted too high and must be
lowered. Go to Counterbalance Valve Adjust-
ment and perform adjustment procedure.
b. If pressure is below 20 684 kPa (3000 psi),
increase engine speed by approximately 300
rpm and observe pressure on gauge.
FIGURE 10-9. COUNTERBALANCE VALVE
1. Check Valves
2. Counterbalance Manifold
3. Power Down Test Port (TPD)
4. Counterbalance Valve
5. Counterbalance Valve Test Port (TCBVP)
6. Power Up Test Port (TPU)
7. Test Port (TR)
8. Pilot Vent Port
9. Needle Valve
10. Counterbalance Valve Port (TCBV)
L10028