An Introduction to Vehicle Restraints: What is a vehicle restraint and why is it necessary?

Before Rite-Hite created the vehicle restraint industry with the introduction of the Dok-Lok® in 1980, facilities relied on simply chocking tires (manually wedging material against a truck’s wheel to help prevent movement) to satisfy the OSHA mandate established in 1978 to address trailer separation accidents. Shortly after the introduction of the Dok-Lok, this requirement was amended to include “an equivalent mechanical means” as an acceptable alternative in 1981. Since then, all facilities have established various vehicle restraint policies based on their loading dock applications.

What is a truck restraint or vehicle restraint system?
Vehicle restraints, or trailer restraints, are devices that latch onto trailers to keep them from separating from the dock during loading/unloading. Along with restraining vehicles, they help improve safety, productivity and security at the loading dock.

What is a dock lock?
A Dok-Lok® (generic term: dock lock) is another term for truck restraint/vehicle restraint. Created and registered by Rite-Hite, Dok-Lok has become the industry term widely used by shippers, distribution centers and warehouses for the past 40 years.

Can you use a Dok-Lok on trailers and trucks?
Yes! The Dok-Lok can latch onto the rear-impact guard (RIG) or rear-wheel of the trailer, depending on loading dock configuration, restraint and truck type. The rotating hook design of many Dok-Loks wrap around the RIG, helping prevent trailer movement while wheel-based restraints restrain the rear-wheel of the trailer to help secure the trailer in place during the loading process.

How do you install a dock lock?
Installation of a vehicle restraint should always be handled by certified technicians who can also provide repair and maintenance services at the loading dock.

What are the different types of vehicle restraints at the loading dock?
There are five types of vehicle restraints that you might find at the loading dock:

  1. Rotating Hook Restraints feature a unique rotating hook design that wraps around the RIG of the trailer, helping to reduce both horizontal and vertical movement during loading activities.
  2. Shadow Hook Restraints add an additional layer of safety by securing intermodal containers or trailers with RIG obstructions.
  3. Vertical Barrier Restraints feature a barrier that runs vertical to the RIG and helps to limit horizontal movement of the trailer. Often a practical option for live loading, Rite-Hite offers Ground Stored, Wall Mounted and Under Leveler style Vertical Barrier Restraints.
  4. Wheel-Lok® Restraints secure the real-wheels of the trailer, rather than the rear impact guard. Because of this, they can work with the largest variety of trailer types including liftgates and trailers without an effective RIG.
  5. Stabilizing Trailer Restraints employ the same mechanics of the hook restraint with the addition of hydraulic cylinders to stabilize horizontal and vertical movement during loading/unloading on the truck, helping provide the smoothest transition from facility floor to trailer bed.

Why do facilities need a vehicle restraint?
Aside from being required by OSHA (29 CFR 1910.178(k)(1) and (m)(7)), vehicle restraints help prevent costly trailer separation accidents, serve as a visual deterrence for cargo theft and help increase productivity and safety at the loading dock.

What is trailer separation and what causes it?
Trailer separation occurs when a trailer inches away from the building or if a truck departs from the loading dock unexpectedly, creating a dangerous gap between the trailer and dock. Material handlers, forklifts and product can unknowingly drive off the edge of dock, into the four foot drop off.

There are five typical causes of trailer separation:

  1. Trailer Creep (Dock Walk). The trailer gradually moves away from the dock due to the repeated momentum created by the forklift traveling in and out of the trailer with sudden starts and stops. Eventually the leveler lip loses contact with the bed of the trailer and a dangerous gap results between the trailer and dock. Air-ride trailers compound the problem.
  2. Early Departure. The truck driver mistakenly pulls away from the dock before loading operations are complete. Oftentimes this is due primarily to lack of communication between truck driver and dock workers. Light communication at the dock helps mitigate this as well.
  3. Landing Gear Failure. Weak or corroded landing gear give way under the impact of loading and the nose of a spotted trailer collapses to the ground, forcing the rear of the trailer, and the RIG, up vertically, and away, horizontally from the loading dock. If not secured, this accident can cause the trailer to tip over, and create a cascading “domino effect” as trailers one by one, are knocked into the adjacent trailer.
  4. Trailer Upending. Often occurring with pup trailers, where the first heavy load placed in the nose of the trailer causes the rear of the trailer to rise, forcing the rear of the trailer, and the RIG, up vertically, and away from the dock.
  5. Trailer Pop-Up. A heavy load on the rear of an empty (or near empty) trailer causes the rear of the trailer to be forced toward the ground, popping the nose of the trailer in the air.

How dangerous is trailer separation?
Trailer separation can be very dangerous. Accidents associated with trailer separation at the dock are documented regularly. Recently OSHA cited 110,000 forklift related in a single year. 

Additionally, the National Institute of Standards and Technology has reported that 7% of forklift accidents occur when a lift truck is driven off a loading dock while OHSA states that 70% of all reported accidents could have been avoided with proper safety precautions. Read more about trailer separation accidents, with illustrations, here.

These accidents are typically very serious and extremely costly due to direct costs of medical care and product and equipment damage, as well as the indirect costs of lost time and increased insurance premiums and shaken morale. Because of this, Dok-Loks are an immediate investment to productivity, safety and security at a facility.

Learn More about Dok-Loks 

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