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Smoracy, LLC
MODEL 3680 HYDRAULIC SECTION
PROCEDURE FOR CHECKING HYDRAULIC PUMP
AND RELIEF VALVE SETTING
Continued from previous page
The Feedwheel Yoke and the Concave Door circuits share a common relief valve so you will only need to use
one of these valves to check system pressure. It is suggested to use the Feedwheel Yoke valve. As with any
circuit using hydraulic cylinders all you need to do is stall it out at the end of its stroke to cause a pressure build up.
The oil from this circuit exits through a power beyond port and is the same oil that powers the valve bank on the
upper right hand side of the cabinet. Because of this, the relief valve setting must be checked here first, and the
pressure must be at least 200 PSI (14 bar) higher then the setting you want at the second valve bank.
The control valve for the Discharge Conveyor Belt also has a diagnostic port. To check the pressure here the
hoses to the hydraulic drive motor must be disconnected and capped to get a pressure reading.
The valve bank on the upper right side of the control cabinet has only one relief valve and therefore only one
diagnostic port to plug a pressure gauge into. When checking the system pressure use only the Feedwheel Yoke
Lock valve at the top of the bank. Remember that you must check the system pressure at the lower bank first
before checking the system pressure here.
Refer to page 75 for the correct relief valve pressure setting for the hydraulic circuit being checked. To begin
checking system pressures place the pressure gauge in the first diagnostic port. With the machine and area
secure, start the engine and open throttle to full RPM’s. With the manual control valve handle centered, the
pressure reading should be less than 180 PSI (12 bar). Push the control valve handle away from you and observe
reading. If the pressure reading is not correct, adjust the relief valve by loosening the lock nut and screwing the
adjustment in or out slowly. If this fails to adjust the pressure the problem may be either with the relief valve or the
pump.
Disengage clutch, turn off engine, wait for the Cutterhead to come to a complete stop, turn Battery Disconnect
Switch off, and you must have the ignition key in YOUR possession. Remove the gauge at the filter head assembly
and set aside. This will break the siphon effect so as not to drain all the oil out of the tank. Attach a hose to the
ball valve located on the manifold inside the control cabinet. Drain the oil from this manifold into a clean bucket by
turning the ball valve on.
With the oil drained remove the relief valve cartridge by unscrewing from the valve body. Make sure that the
o-rings are still on the cartridge, and if they are not remove them from the valve body. Check the cartridge for any
foreign material trapped inside that may prevent the relief valve form operating properly. Check for broken valve
springs or damaged parts. Thoroughly flush the cartridge in a solvent bath and reinstall in the valve body. Unscrew
the valve adjustment a few turns to make sure that its not bottomed out and would not be able to open under
pressure. Close the ball valve on the manifold and replace the gauge in the filter head assembly.
Start engine and attempt to adjust the pressure using the same procedure as before. If the relief fails to adjust
the next step is to swap it with another. The relief valves are common throughout the hydraulic system.
Disengage clutch, turn off engine, wait for the Cutterhead to come to a complete stop, turn Battery Disconnect
Switch off, and you must have the ignition key in YOUR possession. Remove gauge from filter head assembly
again and drain manifold. Remove relief valve in question and swap it with another. After both are tightened in
place, close ball valve at the manifold and replace the gauge in the filter head assembly. Start the engine and again
attempt to make adjustment with the swapped relief valve. If adjustment is possible than the relief valve you started
with is bad and needs to be replace. A new relief valve will need to be checked for proper pressure setting after it
is installed. Any time you are putting a relief valve in it’s a good idea to back off the adjustment a few turns to make
sure its not bottomed out and unable to open. Make final adjustments with the relief valve in the machine. If
adjustment is still not possible the problem lies with the hydraulic pump. A qualified technician with a Hydraulic
Flow Meter unit could confirm your suspicion while the pump is still on the Recycler, or you can remove the pump
and have it repaired or replaced.
Follow this procedure to check the other circuits of the hydraulic system. Reconnect the hydraulic hoses to the
drive motors when you have completed all testing. Check the fluid level in the hydraulic tank to make sure that it is
still 7/8 full.
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