Why is my hydraulic dock leveler not working?

When a hydraulic dock leveler is not working, the cause is usually one of five things: no power to the pump, low or leaking hydraulic fluid, a tripped safety stop (velocity fuse), debris in the pit, or a worn lip hinge or lip cylinder. Check the power and the control box first, then look for oil under the leveler and anything jammed in the pit. If the deck will not rise, drops on its own, or the lip will not extend, take the leveler out of service and call a technician before anyone drives a forklift over it.

How a hydraulic dock leveler works

A hydraulic dock leveler is a steel deck set in a pit at the dock door, with a hinged lip at the front. When you press the button, an electric motor runs a pump that pushes hydraulic fluid into the main cylinder, which raises the deck. At the top of the stroke a second, smaller cylinder swings the lip out. When you let go, the deck lowers under its own weight until the lip rests on the trailer bed, so forklifts can drive across. A mechanical leveler does the same job with springs and a pull chain instead of a pump. Our dock leveler glossary entry explains the parts in more detail.

Common problems and what they usually mean

What you see	Likely causes
Nothing happens when you press the button	A tripped breaker or blown fuse, a failed motor starter or contactor, a bad push button, or an interlock that stops the leveler while the dock door is closed or the trailer restraint is off
The motor runs but the deck will not rise	Low hydraulic fluid, a leaking hose or fitting, a worn pump, or the motor turning the wrong way after electrical work
The deck rises slowly or stalls part way	Low fluid, air in the lines, thick fluid in cold weather, or a worn pump
The deck drifts down on its own	A leaking cylinder seal, hose or valve, or a holding valve that no longer seals
The lip will not extend or will not stay out	A bad lip cylinder, a lip valve fault, a bent lip or a hinge seized with rust and dirt
The deck will not go down	A raised maintenance strut, debris under the deck, a tripped safety stop or a stuck lowering valve
The deck drops suddenly and stops	The safety stop (velocity fuse) did its job after a fast drop, often because the trailer pulled away early

Checks you can make safely

• Power and controls. Make sure the breaker is on and the control box has power. Check whether the leveler is interlocked with the dock door or a trailer restraint and that both are in the right position.
• Oil on the floor. With the deck stored and nobody near it, look under the front of the leveler and around the pit for hydraulic fluid. Fresh oil means a leak in a hose, fitting or cylinder seal.
• The pit. Pallet pieces, shrink wrap, ice and trash collect under the deck and stop it from lowering or leveling. Clear it only with the leveler locked out and the maintenance strut in place.
• The lip hinge. A lip that sticks often has a hinge packed with dirt or rust. Look for bent hinge knuckles or a lip that sits crooked.
• The weather. In a Denver cold snap, hydraulic fluid thickens and a leveler can move slowly until the building warms up. If it stays slow, the fluid level or pump needs a look.

Never stand or work under a raised deck that is held up only by its hydraulics. Every hydraulic leveler has a maintenance strut or safety bar; it must be locked in place and the power locked out before anyone reaches into the pit.

My dock leveler won't go down. What could be the problem?

First check that the maintenance strut is not still engaged and that nothing is jammed under the deck or behind the lip. If the deck still stays up, the lowering valve may be stuck or the safety stop may have tripped. Do not force it down with a forklift or by standing on it. Lock out the power and have a technician reset or repair the valve.

When to take the leveler out of service

Stop using a leveler when the deck drifts or drops on its own, the lip will not stay extended, hydraulic fluid is leaking, the deck plate or lip is cracked or bent, or a weld is broken. Put a cone or a sign on it and close the dock door. OSHA's dockboard rule requires a dock leveler to be strong enough for the load that crosses it and the trailer to be kept from moving while workers are on it, which a leveler that cannot hold its position does not meet. A leaking leveler also puts slick oil on the floor where forklifts turn.

Repair or replace?

Most hydraulic leveler problems are repairs: a hose, a fitting, cylinder seals, a valve, a pump or motor, a lip hinge pin, or new hydraulic fluid. Replacement makes sense when the deck or the pit frame is cracked or twisted, when parts are no longer made for an old leveler, or when the leveler no longer fits the trailers you load. Fixing the dock bumpers at the same time protects a repaired leveler, since missing bumpers let trailers slam into the lip and the front of the pit.

Preventive maintenance for hydraulic levelers

A leveler that is looked after rarely fails without warning. Keep the pit clean, check the fluid level and look for leaks, grease the hinges, test the safety stop and the lip, and check the bumpers and the dock door at the same visit. Many facilities have their dock equipment serviced on a regular schedule along with the overhead doors, so one visit covers the whole dock.

How G Brothers helps

We repair dock levelers, dock seals and dock bumpers, along with the loading dock doors above them, for warehouses and businesses across the Denver metro. We dispatch 24/7 when a dock is down, and can provide a certificate of insurance, usually within 24 hours. See dock leveler, seal and bumper repair and loading dock door repair, read when to replace loading dock seals, or ask for a free estimate.

Sources

• OSHA, 29 CFR 1910.26, Dockboards
• Michigan Overhead Door, Hydraulic Leaks in Dock Levelers: Signs, Risks, and Repairs
• LoadingDock.com, Do I Need To Replace or Repair My Dock Leveler?
• Beauway, Dock Leveler Lip Problems: 3 Common Causes and Fixes