HUSCO GENERAL TROUBLESHOOTING GUIDE
If the hydraulic system does not function proper-
Relief pressures
ly, check the following in the order listed. The hy-
Install a 3000 psi (210,92 kg./cm. 2 ) hydraulic
d r a u l i c oil must be at operating temperature, a
gauge in the verticle pipe on the left side of the
minimum of 150F% (66C), before any of the follow-
front frame. (See diagram). Measure all pressures
ing checks are made. After you have performed the
at this point. This pipe connects the pumps to the
n e c e s s a r y checks and adjustments in one step,
main control valve.
operate the machine to see if the problem has been
corrected.
1. Hydraulic Fluid level (CAUTION: Hydraulic Res-
ervoir must not be overfull.)
2. Free Movement of Spools and Positive Detent
Feel in the Pilot Valve
3. Stall Speed
4. Relief Pressures
5. O p e r a t i n g Times (Boom &. Bucket Reaction
Times)
6. Main Spool Actuating Pressure
Relief pressure adjustments for the Husco valve.
7. Condition of Parts in Inlet Control Section
1. Warm the engine and transmission to operating
temperature. Warm the hydraulic fluid to 150F
8. Condition of Parts in Boom and Bucket Sections
10 (66C4C).
Free movement of spools and positive detent feel
2. Install a 3000 psi (210,92 kg./cm.2) gauge in the
vertical pipe on the left hand side of the front
With the engine shut off, move the control levers
frame.
in the cockpit back and forth to see that the linkage
is not binding and that the spools in the pilot valve
3. Accelerate engine to high free idle, roll bucket
are not sticking. While checking free movement of
b a c k and hold over relief. Read and record
spools, check to see that the detent positions are
positive and operating properly. If the pilot valve
pressure.
spools do not move freely or the detents do not posi-
tion properly, loosen the detent covers until the
4. Accelerate engine to high free idle, raise boom
to maximum height, hold over relief, read and
spools move freely. Then tighten the detent covers
slowly, making sure the spools continue to move free-
record pressure.
ly. If the air tanks have not been drained daily, it's
5. Compare boom up with bucket roll back pres-
possible that the detent mechanism contains water
and is rusted.
s u r e readings. Each should read the same. If
both pressures are low but equal the main re-
l i e f must be adjusted as outlined in the next
Stall RPM
step. If one reading, either boom up or bucket
Measure the stall RPM as outlined in the trans-
roll back is low, adjust the relief cartridge that
mission and converter troubleshooting section of
is low. Boom up and bucket roll back relief car-
this manual. If stall is low the machine will not have
tridges are set higher than main relief. In each
t h e necessary hydraulic power. Remember that
case the gauge should read main relief pressure.
stall must be measured with the engine and trans-
mission at operating temperature and with the main
6. To adjust the main relief, remove the inlet sec-
relief at the correct pressure setting.
tion cover of the main valve. Remove the main
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