Double Speed Buffer-type Four Valve (JL89)

 Ascend 

The elevator ascending speed is adjusted by the VFD which controlled  by PLC, that means the VFD drives the motor and oil pump. 

• After start-up, the elevator accelerates upward.  

• When reaching the preset deceleration position, the PLC  commands the VFD reduce its output frequency to 20–25 Hz for the  deceleration.  

• When the elevator arriving at the leveling position, the PLC controls  the VFD to stop, enabling the elevator to stop accurately

Descend

The elevator descending speed is adjusted by the fast and slow  pilot throttle valves. 

Upon receiving the descending signal, both the fast and slow  solenoid valves are energized, two pilot throttle valves open,  meanwhile the elevator starts to accelerate downward  smoothly.When it reaches the preset deceleration position, the fast  solenoid valve de-energizes and the fast pilot throttle valve closes  gradually, meanwhile the elevator descending slowly.When the  elevator arriving at the leveling position, the slow solenoid valve  de-energizes and the slow pilot throttle valve closes, enabling the  elevator to stop accurately.