Pentalift Blog - October 2019
What is Dock Leveler Lip Crown and Why is it Important?
October 25, 2019, 4:19 pm - When the dock leveler is in the closed/stored position the hinged lip assembly is vertical tucked in behind the front of the dock leveler frame. When the dock leveler is operated the deck raises and the hinged lip rotates outward to the extended position. In the extended position the lip assembly is not parallel with the deck plate it is positioned just slightly lower than parallel to the deck plate, this is referred to as “lip crown”. Dock levelers service varying heights of incoming vehicles; it is important that the dock leveler is able to service trucks that are higher than the dock height. If the lip did not have a crown (if the lip was parallel with the deck surface) with a truck in position above dock height the tip of the lip would project upwards creating a bump when the lift truck enters the trailer and creating a barrier when the lift truck attempts to exit the trailer. It is very important that the hinged lip rest flat on the truck bed when the truck is above dock height, lip crown achieves this purpose. In some applications the dock height and the truck bed height are consistently at the same level, in this case lip crown is not as important therefore the dock leveler can be ordered with reduced lip crown.
Why is Hot Dip Galvanizing Lift Tables so Expensive in Contrast to Other Finishes Available?
October 18, 2019, 4:18 pm - The majority of lift tables receive a sprayed on finish coat, this sprayed on finish coat often includes products such as enamel paint, epoxy paint or even cold spray galvanizing. None of these finishes can compare to the high performance coating of hot dip galvanizing. During the hot dip galvanizing process the components are first dipped into a tank of a cleaning acid solution, removed and then dipped into a separate tank containing the molten galvanizing solution. As opposed to any spray on finish the hot dip process assures all surface areas of the components are completely covered, the high heat of the molten galvanizing solution provides superior adhesion to the steel surfaces. There is not a spray on metal coating that comes close to providing the protection that hot dip galvanizing provides in resisting and preventing corrosion. The hot dip galvanizing costs are all up front and although they can seem to be costly at the time the long term benefits of this superior finish will extend the life span of the equipment. Extending the life span of the equipment (avoiding replacement) far outweighs the initial costs of hot dip galvanizing.
Why are self-retracting lips important on a hydraulic dock leveler?
October 11, 2019, 1:09 pm - Under normal operating conditions the truck is backed into position at the loading dock and the trailer door is opened. The attendant operates the dock leveler, the dock leveler deck raises and the hydraulic lip extends. The dock leveler is then lowered into position with the extended hydraulic lip resting on the bed of the truck. After the loading is completed the attendant returns the dock leveler to the closed stored position, that’s what is supposed to happen. However should the truck depart the loading dock area without first returning the dock leveler to the closed stored position the dock leveler deck lowers automatically with the lip in the extended position. The next incoming vehicle will accidentally or unknowingly impact the extended hydraulic lip causing structural damage. To avoid structural damage to the lip assembly, lip cylinder and lip hinges the dock leveler hydraulic system is designed to permit the lip to automatically slowly retract inward to the vertical position with the lip assembly safely tucked away behind the face of the dock bumpers. This automatic slow retraction of the lip assembly into position behind the dock bumpers eliminates any potential impact by the next incoming vehicle.
Why would you install a velocity fuse on a hydraulic lift table?
October 7, 2019, 8:42 am - 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.