Skid Steer Lift Arm Support: How to Safely Lock Out Arms for Attachment Maintenance

A skid steer lift arm support is the mechanical device that prevents the boom from dropping on you during attachment maintenance. Between 1980 and 1992, the NIOSH National Traumatic Occupational Fatalities database recorded 54 skid steer deaths in the United States. Twenty-five of those cases-46 percent-involved a worker crushed between the lift arms and the machine frame. In Massachusetts alone, four mechanics and operators died between 2009 and 2015 while servicing loaders with the arms raised and no support device in place. Every one of those deaths was preventable.

What a Skid Steer Lift Arm Support Actually Does

A lift arm support is a mechanical device that physically prevents the boom from dropping. It works independently of the hydraulic system. If a hose bursts, a cylinder seal fails, or someone accidentally bumps a control lever, the support holds the full weight of the arms and whatever attachment is mounted on them. There are two basic designs:

• A pin-type support uses a heavy steel pin that slides into a receiver on the boom structure and locks the arms at a fixed raised position.
• A strut-type support (also called a cylinder brace or boom cylinder support) clamps directly onto the extended rod of the lift cylinder and prevents the cylinder from retracting.

Both designs serve the same purpose. They transfer the load from a hydraulic circuit-which can lose pressure at any moment-to a solid mechanical connection that cannot.

The NIOSH Alert on skid steer fatalities (Publication No. 2011-128) documents multiple cases where workers died because the lift arms dropped during maintenance. In two incidents investigated by the Massachusetts FACE program (2009 and 2012), the victims were working directly beneath raised arms with no support engaged. The arms fell and crushed them against the cab frame. In a separate OSHA-investigated case from 2012, a mechanic used a chain hoist attached to the bucket instead of a proper support. The hoist released under load. The mechanic did not survive. Both were predictable result of skipping a 30-second safety step.

Pin-Type vs. Strut-Type: How to Lock Skid Steer Lift Arms by Machine Brand

The type of lift arm support on your machine depends on the manufacturer and model year. For example, Caterpillar uses a strut-type brace mounted near the lift cylinder. The operator pulls a retaining pin from outside the cab, then enters the cab and raises the arms. As the cylinder extends, the brace drops into position on the cylinder rod under its own weight. To disengage, the operator raises the arms fully from inside the cab and lowers them slowly-the brace folds back automatically through a scissor action. The operator never needs to stand under a raised arm to remove the brace.

Bobcat also uses a strut-type support (for example, part number 6718312). The operator raises the arms from inside the cab, then exits to place the support strut over the lift cylinder rod. After returning to the cab, the operator lowers the arms until the strut contacts the cylinder body and carries the full weight of the boom. Only then is it safe to exit the cab for maintenance work.

John Deere machines use what the manufacturer calls a Boom Lock. The specific design varies by model series, but the function is the same-mechanical prevention of arm drop during service.

Case supplies a dedicated lift arm support (for example, part number D124937 for models 1835C, 1838, 1840, and 1845C). Consult the operator's manual for the installation procedure specific to your model.

Regardless of brand, two rules apply everywhere:

• First, use only the support device supplied or approved by the machine manufacturer. NIOSH, OSHA, and every major OEM require this.
• Second, never substitute cinder blocks, jacks, chain hoists, or any improvised device for a proper support. Cinder blocks can shatter under load. Chain hoists can slip. These substitutes have killed people.

Tip from the Skidsteers.com Team: If you bought a used machine and the lift arm support is missing, do not operate with the arms raised until you get a replacement. Contact your dealer or the manufacturer and order the correct part number for your model and serial number. Aftermarket substitutes exist, but the manufacturer's own device is the only one that carries their engineering validation and keeps your warranty intact.

The OSHA Lockout/Tagout Procedure for Skid Steer Maintenance

OSHA standard 29 CFR 1910.147 requires employers to develop written procedures for controlling hazardous energy on all equipment-including mobile machines like skid steers. The regulation applies whenever a worker performs service or maintenance in a zone where unexpected machine movement could cause injury. That includes any work near or beneath raised lift arms.

The full lockout/tagout procedure for a skid steer follows these steps:

1. Park the machine on flat, level ground.
2. Lower the attachment flat to the ground.
3. If the work requires the arms to remain raised, install the manufacturer-approved lift arm support before doing anything else.
4. Set the parking brake. Shut off the engine. Remove the key from the ignition and keep it on your person.
5. Relieve residual hydraulic pressure (see the next section for the step-by-step method).
6. Disconnect the battery. Use the main battery disconnect switch if the machine has one. If not, disconnect the negative cable directly from the battery terminal.
7. Apply a lock and a warning tag to each energy isolation point-the ignition switch, the battery disconnect, and any hydraulic valves. The tag must read "DO NOT OPERATE" or "DO NOT START" and must identify the person who placed the lock. OSHA requires that the tag attachment strap withstand at least 50 pounds of pulling force.
8. Block the wheels with chocks (wheeled machines) or block the tracks (CTL and multi-terrain loaders) to prevent rolling or creeping.
9. Verify zero energy: turn the ignition key to the RUN position (do not start the engine) and try all control levers and pedals. Nothing should respond. If anything moves, stop and find the energy source you missed.

Only after completing all nine steps is the machine safe for maintenance. When the work is finished, reverse the procedure: remove blocks, reconnect the battery, remove locks and tags, and verify that all tools and personnel are clear before starting the engine.

How to Relieve Hydraulic Pressure Before Working Under the Boom

Even after the engine is off, the hydraulic system retains pressure. Trapped fluid in the cylinders and hoses can cause sudden arm movement or a high-pressure spray if a line is disconnected. Relieve that pressure before working near any hydraulic component.

The procedure applies to all skid steers, compact track loaders, and multi-terrain loaders. With the lift arm support already installed and the arms resting on it, shut off the engine. Turn the ignition key to the RUN or ON position without starting the engine. This powers the electrical system but leaves the hydraulic pump idle. Fasten the seat belt or lower the restraint bar. Press the hydraulic activation button (labeled PRESS TO OPERATE or OPERATE on most machines) to unlock the control valves.

Move the boom lift and bucket tilt joysticks or levers through their full range of motion-up, down, left, right-several times. This opens the spool valves in the control valve block and routes trapped pressure back to the reservoir. Cycle the auxiliary hydraulic switches in both directions, or hold the auxiliary pressure release button if your machine has one. For machines with Connect-Under-Pressure couplers, push the coupler housing toward the valve block and hold for five seconds.

Turn the key to OFF. Remove the key and take it with you.

At this point, the hydraulic system holds no residual pressure. The lift arms rest on the mechanical support, not on hydraulic force. The machine is ready for service work.

Tip from the Skidsteers.com Team: Print a one-page lockout/tagout checklist, laminate it, and hang it from the machine's key ring or attach it to the cab wall. A checklist in a binder on a shelf does not get used. A checklist that lives on the key ring gets followed every time.

One critical warning: never use your hands to check for hydraulic leaks. A pinhole leak in a high-pressure hose can inject fluid through the skin at pressures that cause serious tissue damage. Use a piece of cardboard held at a safe distance to detect escaping fluid.

Which Attachment Maintenance Tasks Require a Boom Lockout

Not every maintenance task requires the arms to be raised. The general rule is straightforward: if the work can be done with the attachment resting flat on the ground, keep it on the ground.

Tasks that do not require raised arms include replacing a bucket cutting edge or bolt-on teeth (the bucket sits flat on the ground), replacing a breaker hammer chisel or retention pins (the breaker rests on the ground), and routine greasing of attachment pivot points accessible from ground level.

Tasks that require the arms to be raised-and therefore require a lift arm support-include inspecting or replacing hydraulic hoses that run along the boom or connect to the lift cylinders, servicing the lift cylinder seals or fittings, accessing internal components beneath the cab (machines with a cab-tilt feature require the arms to be raised and locked before the cab pivots), and inspecting or repairing the boom structure itself, including pins, bushings, and weld joints in the arm assembly.

Swapping attachments at the quick attach interface is another situation where the lockout matters. Any time the boom is raised and someone works near the mounting plate and adapter connection-adjusting alignment, connecting hydraulic couplers, or inspecting the locking pins-the lift arm support must be in place first.

The moment you disconnect or loosen any hydraulic line, fitting, or component on the lift circuit, the arms will drop if they are not mechanically supported. This is not a gradual leak-it is an immediate loss of holding force. The support must be in place before you touch the first fitting.

Skid Steer Lift Arm Lockout Device: Inspection, Wear, and Replacement

A lift arm support is a safety-critical component. Inspect it before every use, the same way you inspect seat belts, fire extinguishers, and ROPS structures. The inspection takes less than a minute.

Check for cracks, bends, or twisting in the support body. Look for missing or damaged retaining pins, cotter pins, or locking knobs. Examine any cables or straps (where applicable) for fraying or corrosion. Confirm that the support seats fully and locks securely in its operating position.

If the support shows any visible damage-any crack, any deformation, any missing fastener-remove it from service immediately. Do not attempt to weld, straighten, or repair a damaged support. Replace it with a new OEM unit. The cost of the replacement part is trivial compared to the cost of a failure under load.

Aftermarket replacements designed as direct-fit substitutes are available on the market for many models. NIOSH and OSHA guidelines consistently recommend using manufacturer-supplied or manufacturer-approved devices. Using an unapproved support may void the machine warranty, and it may not meet the load and engagement specifications that the OEM device was engineered to handle.

Why the Seat Interlock Does Not Replace a Lift Arm Support

Modern skid steers include an operator presence system, also called a seat interlock. When the operator raises the restraint bar or leaves the seat, the system disables the hydraulic controls. The arms cannot be raised or lowered from the controls while the seat is empty.

This is a valuable safety layer-but it does not replace a mechanical lift arm support. The interlock prevents unintended control inputs. It does not protect against hydraulic failure. If a hose bursts, a fitting cracks, or a cylinder seal fails while the operator is out of the seat, the interlock cannot prevent the arms from falling. Only a mechanical support can hold the boom in that scenario.

NIOSH investigation reports confirm this distinction. In several documented fatalities, the seat interlock was functioning correctly at the time of the incident. The arms dropped because of hydraulic failure, not because someone operated the controls. The interlock did exactly what it was designed to do-and it was not enough, because the lift arm support was not engaged.

Treat the interlock and the mechanical support as two independent safety layers. Use both. Always.

Tip from the Skidsteers.com Team: Add the seat interlock to your daily pre-start check. With the engine running and the restraint bar raised, try moving the boom controls. Nothing should respond. If the arms move with the bar up, the interlock is faulty. Shut down and repair it before operating the machine.

Differences Between Wheeled, CTL, and Multi-Terrain Loader Lockout

The core OSHA lockout procedure is the same across all three machine types. The lift arm support works identically whether the machine rides on tires or tracks. The differences are in the undercarriage, not the boom.

Wheeled skid steers require wheel chocks placed against all four tires to prevent rolling during service. On any slope-even a slight one-an unchocked wheeled machine can roll when the parking brake is released during maintenance.

Compact track loaders and multi-terrain loaders require blocks or chocks placed against the tracks. These machines carry additional stored energy in their track tensioning systems (hydraulic or spring-loaded). Before working on the undercarriage, verify that track tension is within specification and that the tensioning mechanism is not under abnormal pressure.

The lift arm geometry-radial lift or vertical lift-affects how the support device engages, regardless of undercarriage type. Radial-lift machines typically use a strut that drops onto the lift cylinder rod and is secured with a pin. Vertical-lift machines often use a built-in lock pin activated by a lever beside the operator's seat inside the cab. Check your operator's manual for the specific engagement method on your machine.

Whether you run buckets, pallet forks, grapples, or breaker hammers-the lockout procedure applies every time you work under or near the raised boom. The attachment on the quick attach plate does not change the requirement. The arms weigh the same and fall just as fast regardless of what is mounted on them.

At skidsteers.com, you will find a full range of American-made attachments for skid steers, compact track loaders, tractors, and telehandlers-all built with U.S. steel and backed by experienced product specialists who can match the right tool to your machine. Every attachment swap starts and ends at the quick attach interface, and every swap is safer when the lift arm support is engaged.