∙ Rest Position: Pressure lock valve is at stand-by, the solenoid LE de-energized and the main flow guide LV closed, preventing flow from cylinder to tank.
∙ Up Travel: During up travel with the pump running, oil flows through port T, through the flow guide LV and out thorough port Z to the main cylinder. Solenoid LE is not energized.
∙ Down Travel: For the car to have a down travel, the pressure lock valve should be energized approximately 0.5 second earlier than the main control valve. This enables the oil to escape from the pilot chamber and allows the main piston LV to open. Else, the pressure between the pressure lock valve and the control valve connecting line drops considerably and to make the elevator operational, the connecting line needs to be re-pressurized again. This can be done by starting the elevator for a short time in the up direction or by pumping oil using a hand pump. Re-pressurizing may also be needed if the main control valve has an internal leakage. Opening of the LV allows the flow of oil from the cylinder to the tank (from Z to T) via the pressure lock valve andthe main control valve.
To stop the elevator, the solenoid LE on the pressure lock valve is de-energized together with the down solenoid of the main control valve (e.g. solenoid D of control valve). In this way, the piston LV in the pressure lock valve and the down piston X in the main control valve closes completely.
∙ Pressure Drop: The pressure loss of the pressure lock valve depends on the size of the valve and the flow rate. The size and type of connectors used also influences the pressure losses. The pressure loss of the pressure lock valve should be taken into account while the main control valve empty car pressure is calculated.
∙ Emergency Down: The emergency manual lowering LH on the pressure lock valve is to be operated to bring the car down in emergency. The down speed of the car is determined by the setting of LY. As the LH is open, oil from the cylinder flows back to the tank through a return tank-line attached to the tank port TN. The return tank-line should not be smaller in size than the tank port TN, else the emergency manual lowering may not function properly. The slack rope valve LK prevents the sinking of the ram when the manual lowering LH is operated in a 2:1 roped elevator to prevent a tangled rope condition.
∙ Air Bleed: After connecting the pressure lock valve or right after servicing the pressure lock valve needs to air-bleed to ensure its functionality. It is sufficient to operate the emergency lowering valve or loosening the solenoid tube slightly until oil is visible and tightening it again.
∙ Manual Down Speed LY (¾˝, 1½˝, 2˝ and 2½˝ valve):
‘in‘ (clockwise) provides a slower, ‘out’(counter-clockwise) a faster down lowering speed.
∙ Slack Rope Valve LK: The LK is adjusted with a 3 mm Allan key by turning the screw LK 'in' for higher pressure and 'out' for lower pressure. With LK turned all the way 'in', then half a turn back out, the unloaded car should descend when the LE solenoid is energized. Should the car not descend, LK must be backed off until the cart just begins to descend, then backed off a further half turn to ensure that with cold oil, the car can be lowered as required.
In order to check the functionality of the pressure lock valve, the solenoid LE can be de-energized during down travel. Alternatively the pressure lock valve can also be tested by unscrewing the retaining nut MM and manually lifting the solenoid coil M.
Caution! Once the coil M is removed from the solenoid tude DR, the energized coil will begin to overheat after 10 seconds, holding it out longer may result in burning of solenoid coil.
The test may result in pressure drop in the connecing line between the pressure lock valve and the control valve. In order to make the elevator operational, the connecting line needs to be pressurized again. This can be done by using the hand pump to move the cabin over a small distance in up direction. Pressurizing the line might also be necessary in cases where the pressure loss between the pressure lock valve and control valve is high for e.g. due to internal leakage.
Pressure Lock Valve
Warning: Only qualified person should adjust or service valves. Unauthorized manupulation may result in injury, loss or life or damage to equipment.
Prior to servicing internal parts, ensure that the elecrical power is switched off, ball valve is closed and residual pressure in the valve is reduced to zero. Very high pressure spikes could result in deformation and oil splashing, this could cause serious injuries.
Description: The pressure lock valve is a solenoid operated check valve designed for hydraulic elevators and includes a self-closing manual lowering valve. Its purpose is to allow free flow of oil from the pump unit T to the cylinder Z for upqard travel and to prevent flow in the reverse direction from Z to T until and electrical signal is given to the solenoid.
Installed in the main cylinder line directly adjacent to the main elevator control valve, the pressure lock valve can be employed as a safety back up valve to the down system of the main control valve to prevent unwanted down movement for the elevator should an eletrical or mechanical malfunction occur in the main control valve.
Another application of the pressure lock valve is to reduce the amount of bounce in a hydraulic elevator system due to the compressibility factor of oil between the cylinder and the control valve by mounting the pressure lock valve onto the cylinder connection.
A slack rope valve LK for roped elevators (e.g. 2:1 indirect transmission) is optional. It prevents the slack rope condition caused by the lowering of the ram when the car is suspended in the safeties or resting on the buffers.
Attention: For manual lowering connect port T with tank.
A→B Free flow. Solenoid LE not energized. B→A Flow only when solenoid LE energized.
LV Check Valve
LH Manual Lowering
LK Slack Rope Valve (Option)
PB Pressure Gauge
LY Manual Down Speed Adjust
(not with 1/2 ̋ pressure lock valve)
A Control Valve Connection
B Cylinder Side Connection
T Tank Return Line