Friday, December 14, 2007
How to Bridge the Gap between Dock Edge and Trailer Bed?
At the edge of dock height, the dock plate or leveler bridges the gap (open space) between the dock edge and the rear of the trailer bed. The dock plate or leveler is the factor that assures high employee productivity and safety. The height variation between the dock edge and rear of the trailer bed is the major factor determining the type of mobile pallet handling equipment that is used in the dock function. The other dock plate or leveler selection factors include the frequency of deliveries, unit-load handling equipment, type of dock concept, and available capital.
Dock equipments which are able to bridge the gap are as follow:
(1)Portable Walk Ramp
The portable walk ramp is an aluminum ramp that is designed with a skid-resistant deck and is used at a truck dock or a grade-level facility. The ramp is up to 3ft in length to bridge a 9-in height variance. The ramp is up to 16ft long to bridge a 5ft height variance and handles loads of up to 1300lb. Beveled ends and a 11-in lip permit an even passage for an employee with a two-wheel hand truck between the truck bed and the floor or ground. Side curbs on the walk ramp reduces the overall usable width by 2 ½ in, but improves safety. The ramp handles a low volume, has a low capital investment, permits side delivery truck door loading and unloading, and enables a two-wheel hand truck or employee to move the product.
(2) Portable Dock Plate
The portable dock plate with an equalizing bend is an aluminum plate with a length of 2 to 5 ft and width of 5 to 6 ft and handles a height differential from 3 to 10 in. At the truck dock, a short plate handles a low height differential and a long plate handles a high height differential. To reduce mobile warehouse pallet handling equipment skids, the dock plate has a diamond-pattern surface. To secure the plate position in the gap, the plate has a locking leg (T-bar) that is attached to the underside and fits into the gap.
(3) Portable Dock Board
The portable truck dock board with an equalizing bend is an aluminum device that permits an electric pallet truck or a rider fork-lift truck to unload and load trailers. To reduce skids, the dock board has a diamond-pattern surface, and to secure the dock board in the gap, locking legs (T-bars) are attached to the underside and are inserted in the gap. Yellow-painted safety curbs help eliminate equipment runoffs. The dock board weight requires powered mobile dock equipment to move and position the dock board in the required dock position. When fork-lift trucks are used in the dock area, some dock plates have fold-down loops or lifting chains to assist in relocation and positioning of the dock
(4)Mobile Yard Ramp
For facilities at grade (ground) level, a mobile yard ramp, ranging from 30 to 36ft in length, permits a lift truck to unload or load a trailer. The ramp has aluminum or steel grating platform and a usable width that ranges between 4ft 5-in and 7ft 4-in. Side guards on both sides reduce powered equipment runoff. Dual wheels are located under the center, and a tow bar permits a lift truck to tow and position the ramp. At the required location, some mobile ramp models have a hydraulic system for easy ramp positioning onto the truck bed and a level-off top for lift truck maneuvering and removing pallets that are at the rear of the delivery trailer.
(5) Recessed Dock Leveler
For facilities that have a truck dock edge at 4ft height, the recessed dock leveler method is most commonly used to bridge the gap. Each dock leveler is installed in a pit or in a cutout of the warehouse floor. It has a diamond-pattern surface with a lip. As required, the dock leveler surface is raised up with a lip that extends outward and lowers to rest on the rear of the delivery trailer bed.
(6) Hydraulic Recessed Dock Leveler
The hydraulic recessed dock leveler has a hydraulic pump and motor in the pit that moves the dock plate to the desired elevation. The dock leveler controls are push buttons. The buttons are located on the interior of the building wall that is adjacent to the dock position.
(7) Mechanical Recessed Dock Leveler
It has a diamond-pattern surface and upwardly biased ramp with a spring mechanism that is held down by a releasable ratchet device. To operate, the employee walks onto the ramp and pulls on the release chain that is connected to the ratchet mechanism. This pulling of the ratchet releases the ramp, and the ramp rises to its uppermost position.
(8) Vertically Storing Dock Leveler
The vertically storing dock leveler consists of a ramp that is withdrawn in the vertical position inside the building.
With this, the dock employee controls the lip and ramp with push buttons from a control panel that is located on the interior of the building wall. After use of the dock leveler, the vertically storing dock leveler ramp is locked in the vertical position. At this point, the leveler is pushed by the employee to another dock position.
The mechanical vertically storing dock leveler is manually moved between dock positions. Generally, the lip is in the extended position; however, if required, the lip is manually retracted. At the required dock position, the dock employee manually lowers the ramp onto the trailer bed. Counterbalanced springs assist in the lowering effort. When not in use the ramp is returned to the vertical position.
(9) Edge-of-Dock (EOD) Leveler
The EOD leveler is a hydraulic or manual device. An employee controls the hydraulic dock leveler with push buttons located on the interior wall of the building. When activated, the hydraulic model pushes the ramp upward with the lip in the extended position. After receiving full extension, the lip is lowered onto the rear bed of trailer.
With the manually operated model, counterbalanced springs assist in raising and lowering the dock leveler.
(10) Front-of-Dock Leveler
The front-of-dock (FOD) leveler is a bridge device that has its own built-in bumpers and is bolted to the concrete edge of the dock. The device is available with a ramp length of 30 in and width of 72 in. The dock leveler is available in both high and low-profile types with a standard projection of 11 in. A special grocery industry model has a 14-in lip projection for placement in a trailer that delivers perishable food items. The high-profile bridge device serves a height differential of 6 in above and 4 in below; and the low-profile device, 4 in above and 1 ½ in below.
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11:42 PM