Hydraulic Car Lift

This is an example that shows the use or our basic hydraulic models. It represents a car lift powered by a pump with an ideal "motor" (i.e. a pure angular velocity source running at 1800 RPM (188.5 rad/sec). The pump flow is controlled by a valve (vlv1), which allows flow to the extend port of the actuator(cyl1), lifting the 2000 kg vehicle.

A second valve (vlv2) is controlled by the same translational displacement source, but it responds opposite to vlv1. That is, when vlv1 is open, vlv2 is closed, and vise-versa. When vlv2 is open, the fluid in the actuator can exhaust back to the reservoir, allowing the vehicle to drop slowly. There are also two leak paths modeled, one is internal to the pump, and the other is indicated by the fixed orifice from the actuator extend port to the reservoir.

Fluid compressibility is modeled in the components that have significant volume, including both the variable volume of the actuator, and the constant volume element (vol1). Any ringing observed in the waveforms is due to the interaction between the mass of the vehicle and the compressibility of the fluid.

Mike Donnelly's picture



Mike Donnelly

Joined November 8, 2013
Design added Thursday, September 22, 2016 | 10:40 am PDT