Hawk Industries Hawkjaw Sr. Manual ALS Serial Numbers 1 to 100 - Manual (Page 75)

Trouble Shooting
Symptom Remedy
RaiseButton/
Lower Button
(cont)
z
Make sure the hydraulic power unit is shut down.
Press the Grip button repeatedly to bleed hydraulic
pressure. Access the main hydraulic block. See
Maintenance & Repair, p. 66, Drawings, p. 114.
Check the Port VR/L sandwich valve H6 flow
setting. No fluid will flow to the Raise/Lower
cylinder if the flow setting is rotated clockwise to
refusal. See Troubleshooting, p. 93.
z
Check that air is reaching the Raise/Lower
hydraulic valve. Make sure the hydraulic power
unit is shut down. Press the Grip button repeat-
edly to bleed hydraulic pressure. The Raise black air
hose connects to Port B on the Raise/Lower
hydraulic valve VR/L. Disconnect the Raise button
black air hose from the Raise/Lower hydraulic valve
VR/L. To disconnect the air hose, push the hose and
collet ring into the valve pilot port. While holding
down the collet ring, pull out the Raise black air hose.
Place your hand over the disconnected Raise black
air hose, and push in the Raise air button. A steady
blast of air should come out of the hose. If no air
comes out of the hose, replace the air logic system.
See Drawings, p.126. If air comes out of the hose
when the Raise air button is pushed in, proceed to
the next step.
z
Check that air is reaching the Raise/Lower
hydraulic valve VR/L at Port A. Disconnect the
Lower green air hose to the Raise/Lower hydraulic
valve VR/L Port A. To disconnect the green air
hose, push the hose and collet ring into the valve pilot
port. While holding down the collet ring, pull out the
green air hose. Place your hand over the
disconnected Lower air hose. Push in the Lower
button. A steady blast of air should come out of the
hose when the Lower button is pushed in. If no air
comes out of the hose, replace the air logic system.
See Drawings, p.126. If air comes out of the green
hose when the Lower button is pushed in, replace the
Raise/Lower hydraulic valve VR/L. See Drawings,
p. 114, 128.
Push in the Raise button or the
Lower button, and nothing
happens. (cont.)
Trouble
Shooting
Troubleshooting 75