Most lift tables are operated using a straight forward hydraulic design. An electric motor coupled to a hydraulic system pumps oil into the lift cylinder(s) which in turn raises the lift table. When the lift table is in the correct position the operator releases the up button and the lift table stops moving. In this elevated position the hydraulic oil is “locked” in the lift cylinder(s). In the event of a hydraulic hose rupture or fitting failure the lift table would drop quickly and at an uncontrolled rate. The uncontrolled descent rate is based on the amount of weight that is on the lift table platform, the more weight on the platform the faster it lowers. Velocity fuses monitor the flow rate of the oil leaving the hydraulic cylinder; if the flow rate (measured in gallons per minute) exceeds the rating of the velocity fuse the velocity fuse instantly closes locking the hydraulic oil in the cylinder. The locked velocity fuse stops this downward fall and are often installed at the base of the lift cylinder. In the ongoing effort to promote worker safety always specify that velocity fuses be installed on hydraulic lift tables.
Oct 07, 2019
