Vestil CART-DS-1000 (DC) - Manual (Page 12)

Remember to unplug the charger before moving the equipment to prevent damaging the cords,
receptacles, and other equipment.
Operating the battery with a low battery voltage might cause premature motor contact failure.
H YDRAULIC SYSTEM O PERATION :
An electric motor directly coupled to a gear-type hydraulic pump produces the fluid pressure and flow the cylinder
requires to raise the deck and a load. A hydraulic manifold bolted directly onto the gear pump houses the
hydraulic control components. The hydraulic components are all rated for 3,000 psi working pressure.
Key components and specifications of the power unit include:
• Electric motor: powered with a 12 VDC battery.
• Gear pump: shaft coupled directly to the shaft of the electric motor.
• Check valve: prevents backflow of fluid through the pump. It allows the deck to hold a given elevation
indefinitely.
• Pressure relief valve: opens a path for fluid to follow back to the reservoir if the fluid pressure exceeds
3,000 psi.
• Lowering solenoid valve: an electrically-operated cartridge valve that includes a screen to keep
contaminants out of the valve.
• Pressure-compensated flow control spool: located under the lowering valve; it regulates fluid flow back to
the reservoir when the valve opens. It allows the deck to lower at a consistent rate when loaded and
unloaded.
• Hydraulic lift cylinder: single action.
• Safety velocity fuse: installed in the hose port of the cylinder. It closes automatically if a catastrophic
hose failure occurs, which prevents the lift table from collapsing. Once activated, the deck remains
stationary until pressure is reapplied to the system.
• Hydraulic fluid: uses HO150 hydraulic fluid. Any anti-wear hydraulic fluid with an SUS viscosity of 150 -
200 at 100°F (SAE viscosity grade of 32) such as AW-32 or Dexron transmission fluid is acceptable.
To raise the deck, press the “UP” pushbutton. The motor turns and spins the hydraulic gear pump. Oil is drawn
from the reservoir through the suction filter and into the pump. The pump pushes pressurized oil through the
check valve and out to the lift cylinders.
To lower the deck, press the “DOWN” pushbutton. The lowering valve opens, which bypasses the check valve,
and the oil in the cylinder returns to the reservoir through the return hose. The deck lowering rate is regulated by
an internal pressure-compensated flow spool.
If the deck continues to slowly lose elevation even after you release the “DOWN” button, remove the lowering
cartridge valve for inspection and cleaning:
• Remove any load from the platform.
• Raise the lift and then lower the maintenance props. Guide the props into the cylinder push assembly as
you lower the platform. Hold the DOWN pushbutton until the lift rests on the props.
• Remove the nut that fastens the solenoid coil to the valve stem; then remove the coil. Unscrew the valve
from the manifold.
• Inspect the valve for contaminants.
• Inspect the o-rings and back-up washers of the valve for cuts, tears, or other damage.
• Immerse the valve in mineral spirits or kerosene; use a thin tool like a small screwdriver or hex wrench to
push the poppet in and out several times from the bottom end of the valve. The valve should move freely
by approximately 1/16” between the closed and open positions. If it sticks in, the valve stem might be
bent and should be replaced if it doesn’t free up after cleaning. Remove mineral oil from the valve with
compressed air; move the poppet in and out at the same time.
• Inspect the bottom of the valve cavity in the manifold for contaminants.
• Press on the middle of the flow control spool with a thin tool. The flow control spool is located in the
bottom of the valve cavity. The spool should move freely.
• Reinstall the valve into the manifold and tighten the valve with approximately 20 lb-ft of torque.
If the deck lowers either extremely slowly or not at all, the culprit might be air in the hydraulic cylinders, which
could cause the velocity fuse in the cylinder to close. To correct the problem, bleed the air from the system:
• Unload the cart.
• Fully raise the deck and then install the maintenance props. Hold the DOWN pushbutton until the rollers
firmly contact the props.
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