All models of Pentalift dock lifts are provided as standard with an external 1 HP power unit. A 1 HP power unit powers any capacity of dock lift. However a 1 HP power unit may result in too slow of a lift speed dependent on the application. This concern becomes more prevalent for higher capacity dock lifts based on the additional quantity and volume of cylinders required to achieve the increased capacity. A good and normal target lift speed for dock lifts is in the 10’ – 12’ per minute range.
The power unit consists primarily of an electric motor connected to a hydraulic pump to raise the dock lift platform and an electric lowering valve that when opened lowers the dock lift platform. The lifting and lowering functions are typically controlled by a hand held 2 button push button assembly.
This link connects to a photograph of various power unit configurations. View Page
The lift speed of a dock lift is determined by how quickly the lift cylinders are filled with hydraulic oil at the required lifting pressure.
The higher the dock lift lifting capacity the greater the number of lift cylinders is required. Increasing the number of lift cylinders increases the volume of hydraulic oil at the required pressure to operate the dock lift and maintain a reasonable lift speed.
To increase the lift speed the power unit’s pump GPM (gallons per minute) flow rate increases while maintaining the same pressure. A larger GPM output pump (providing the same pressure) requires a proportionally higher horsepower rated lift motor to drive the higher volume output pump.
The most common dock lift power units are rated 1 HP, 5 HP, 7.5 HP and 10 HP; the higher HP rated lift motor drives a higher volume output pump increasing the volume of hydraulic oil pumped to the lift cylinders therefore increasing the lift speed.
It should be noted that lowering speeds are not significantly influenced by the motor horsepower of the power unit. Regardless of the power unit horsepower lowering speeds remain mostly consistent and the same. Most lifts are gravity lowered and lowering speed is determined by a flow control valve.