Original Publication Date: 1982-Apr-01
Included in the Prior Art Database: 2005-Feb-09
AbstractThis article discloses a lifting mechanism which has all the es advantages of hydraulic operation without requiring hydraulic pumping mechanisms.
This article discloses a lifting mechanism which has all the es advantages of hydraulic operation without requiring hydraulic pumping mechanisms.
In some lifting apparatus, air cylinders are used to lift mechanisms. The drawback with such air cylinders is that, because air is highly compressional, the cylinders do not move smoothly until the air pressure reaches a critical lifting point and then the cylinder starts extremely rapidly so that the motion of the shaft in the cylinder is practically a step function. In many cases this rapid acceleration in overcoming the initial friction of the shaft is detrimental and cannot be tolerated.
Smoother operation can be achieved using hydraulic mechanisms, but such hydraulic mechanisms usually require a pump which is expensive and requires substantial maintenance.
This article discloses an air-driven hydraulic cylinder 10 which avoids the step function of the movement of the piston in the cylinder and eliminates the necessity of using a hydraulic pump. The unit shown in the figure comprises a cylinder 10 having a moveable shaft 11 and an air supply 12. The air supply is directly connected to the return portion of the cylinder 10 by virtue of a line 13 and to a reservoir 14. The reservoir 14 contains a substantial amount of hydraulic fluid and has an output 15 coupled through a braking mechanism 16 and a hydraulic fluid speed control 17. The hydraulic brake is basically a solenoid for shutting off the line, w...