Pentalift Blog - December 2019
How does a lift table hydraulic velocity fuse work?
December 13, 2019, 10:53 am - If this option is ordered the hydraulic velocity fuse is installed in the return line of the lift table’s hydraulic circuit. As the lift table starts to lower the hydraulic oil flows out of the lift cylinder(s) and through the velocity fuse to the power unit reservoir. Depending on the model of lift table the velocity fuse is installed directly on the base of the lift cylinder or in a common manifold that monitors the returning oil flow rate from a bank of multiple lift cylinders. Velocity fuses are readily available commonly used and rated in GPM (gallons per minute) of hydraulic flow. For example a 5 GPM rated velocity fuse will allow up to 5 gallons per minute of hydraulic oil to flow freely through the valve without mechanical interruption. In the rare event of a hydraulic line rupture with a loaded lift table in the raised position the hydraulic oil flow rate leaving the lift cylinder(s) will increase both immediately and significantly. If this increased flow rate exceeds the velocity fuse rating an internal valve in the velocity fuse mechanically closes instantly trapping the oil in the cylinder(s) and successfully arresting the downfall of the lift table.
What is dock equipment pit curb angle and who provides it at a construction site?
December 6, 2019, 3:30 pm - Dock levelers and dock lifts are 2 of the most common products used at a loading dock area and are generally installed into a pre-formed concrete pit. Prior to the equipment arriving at the construction site the pits are first formed. The pit curb angle is required at that time to form the pit to the manufacturer’s specified length, width and depth. The pit curb angle is manufactured from steel angle iron and has tangs or J bolts welded to the inside of the angle for the concrete to “knit” around when the concrete is poured. As the concrete cures these tangs or J bolts solidly secure the curb angles in position. Although pit curb angle is often available it is seldom ordered by the contractor directly from the manufacturer. The primary reason is the pits are often formed well before the dock equipment is required on site, often months in advance. The total costs for the manufacturer to supply and ship the curb angle ahead of the equipment can significantly exceed the cost of sourcing the pit curb angle locally. Sourcing the curb angle locally also minimizes any potential for mis placed or damaged goods that can occur during shipment from the manufacturer. Traditionally it is most common for the contractor to source the curb angle locally through a miscellaneous metal supplier; the local miscellaneous metal supplier fabricates the curb angle to the manufacturer’s pit drawing guidelines.