There are several operating conditions which must be met before a hydraulic motor driven centrifugal pump can pump liquid.
If the shaft is not turning, check the first and second step. If the shaft is turning, go to the third step.
First
, the impeller, shaft, and gears must turn freely. The hydraulic motor is a low torque motor and will not overcome a bound
up shaft. Corrosion can form between the impeller and the volute or in the seal area. With the tractor off, reach inside the
suction port of the volute with your fingers and see if the impeller can easily be turned by hand.
Second
, hydraulic oil must flow across the gears in the motor. Check the needle valve to make sure it is set according the
instructions on pages 4 and 5. If the needle valve is backed out, oil will by-pass the gears and fail to turn the shaft.
Trapped pressure in the hydraulic couplers may also prevent flow across the hydraulic motor. Reverse the hydraulic control lever
to momentarily pressurize the return hose. This action will open the quick coupler valve and relieve the trapped pressure.
Third
, the pump must be primed. The pump will not operate unless the volute cavity is completely full of liquid when started.
Remove the top pipe plug on the volute to verify that only liquid comes out. Refer to PUMP MOUNTING section on page
three.
There are several factors which may contribute to a pump’s inability to develop pressure.
They are: 1) insufficient shaft speed; 2) restrictions in the plumbing; 3) internal leakage in the pump.
C
heck the SHUT-OFF PRESSURE according to the instructions on page 4. If the Shut-off Pressure is per the specifications,
then the pressure drop is due to restrictions in the plumbing. If the shut-off pressure is below the specifications, it could be
due to insufficient shaft speed or internal leakage in the pump.
Restrictions in the plumbing:
For every length of hose, valve, strainer, and fitting between the pump and the boom, there
is a loss of pressure. Check for clogged strainers, collapsed hoses, standard port valves, and undersized plumbing.
Insufficient shaft speed:
The pressure created by a centrifugal pump is a function of the pump shaft speed. The shaft
speed is determined by the flow rate of hydraulic oil going across the gears. A tractor dealership can use a hydraulic flow
meter to verify the GPM of oil flow going to the hydraulic motor. For instructions on how to adjust the shaft speed, refer to
the section on pages 4 and 5 titled: REGULATING HYDRAULIC FLOW TO THE SPRAYER PUMP.
Internal leakage in pump:
In centrifugal pumps, there is a close fit where the eye of the impeller fits into the inlet port of the
volute. This close fit seals the low pressure suction liquid from the high pressure liquid inside the pump. If either the impeller
or volute are worn, then the pump will not develop pressure because liquid pressure leaks through this area. If there is
significant play when the eye of the impeller fits into the inlet port of the volute, replace the impeller and/or volute.
Ace Pump Corporation
P.O. Box 13187 - 1650 Channel Avenue
Memphis, TN 38113
www.AcePumps.com
Phone: 901-948-8514
Fax: 901-774-6147
Ace Form # HYD-MAN
Revised 12/11
TROUBLESHOOTING
WILL NOT PUMP LIQUID
WILL NOT DEVELOP PRESSURE
SEAL LEAKS
Refer to the sections titled MECHANICAL SHAFT SEALS on page 5 and HYDRAULIC MOTOR SEALS on page 3 for
information on reducing the frequency of seal failures.
When a pump starts out at the correct pressure and then gradually looses pressure over a period of several hours, the likely
cause is due to the hydraulic oil heating up. As hydraulic oil heats up from 90 degrees Fahrenheit to 150 degrees, the pump
performance will decrease 30%. Typically, the heat added to the system is due to energy losses caused by large bypass
flows and restriction. Improper regulation of hydraulic oil to the Ace motor can cause the oil to heat up (refer to pages 4 and
5 for setup instructions).
LOSES PRESSURE GRADUALLY OVER SEVERAL HOURS