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ZLS Lifts

The lift will not raise?

  1. Check the actual weight of the load. The rated capacity of the lift is: ZLS2 2000 lb. - ZLS4 4000 lb. - ZLS6 6000 lb.
  2. If the motor is not running, check the main disconnect switch, the fuse(s) and the wiring to the motor.
  3. The hydraulic oil level may be low. When the lift table is lowered, the oil should be 1/2" to 3/4" (13 to 19 mm.) below the top of the tank. Add oil as necessary.
  4. The motor voltage may be too low. Check the voltage when the motor is under load. The supply voltage should be within +/- 10% of the rating.
  5. The suction filter may be clogged. Clean the suction filter.
  6. A vacuum leak may be allowing air into the suction line, causing cavitation (loss of suction) in the pump. Check all fittings in the suction line, and tighten or replace as necessary. CAUTION! If cavitation is allowed to continue, the pump may be damaged, and may have to be replaced.
  7. For the lift to raise, the down-valve must be de-energized and fully closed. Check for a problem with the wiring to the down-valve. Check the solenoid in the valve with a voltmeter. The valve must be clean and free to operate. To check this, remove the solenoid and then the valve. Look for dirt or metal chips that could block the valve action. Clean the valve plunger with kerosene, then blow it clean with compressed air. The expansion nut that holds the solenoid should be finger tight only!
  8. If the pump has been changed, the coupling between the pump and motor may not have been installed.

 

The lift elevates but will not hold a load.

  1. Raise the table top completely, and insert the maintenance devices.
  2. The check valve may be leaking. Dirt on the valve seat will prevent the valve from closing fully. The check valve is mounted in the pump housing, as shown in Fig. 10. Remove the check valve cap and inspect the valve for dirt or metal chips which may be preventing it from closing. You may be able to restore the seal by lightly rapping the ball into the seat using a 1/4" diameter rod and a small hammer.
  3. The down-valve may be energized. While the lift is holding a load, the down-valve should be de-energized and fully closed. Check the solenoid in the valve with a voltmeter. The valve must also be clean and free to operate. To check this, remove the solenoid and then the valve. Look for dirt or metal chips that could block the valve action. Clean the valve plunger with kerosene, then blow clean with compressed air. The expansion nut that holds the solenoid should be finger tight only!!
  4. The cylinder may be leaking. Look for oil on the cylinder rod and in the vent line. (This may also occur if the oil tank has been over-filled.) If you find much oil in either place, and the tank is not over-filled, the cylinder should be repacked. See Repacking Southworth Lift Cylinders.