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Chocking and Blocking Equipment

Chocks stop things from rolling. Blocking stops things from falling. Both are cheap, simple and skipped far too often, usually right before someone gets hurt.

What is the difference between chocking and blocking?

Chocking means placing wedges against wheels to stop a vehicle or trailer from rolling. Blocking, also called cribbing, means supporting a raised load with solid stands, timbers or purpose-built jack stands so it cannot fall. You often need both on the same job.

A jack, a hydraulic cylinder or a loader arm is a lifting tool, not a support. Seals leak, valves fail and levers get bumped. Anything you or another person will be under or beside should rest on proper support.

On a farm the typical case is a tractor and a trailer parked on a yard with a little grade. It never feels like much of a slope until the trailer coupler comes off and the tongue drops. That is the moment a loose trailer goes for a roll, so chock first and unhitch second.

• Chocks stop rolling
• Blocks stop falling
• Jacks and hydraulics only lift
• Use both when the job calls for it

When should you chock wheels?

Chock whenever you park on a slope, hook up or unhook a trailer, work under a tractor, change a tire, or leave a machine with the engine off near people. Chock a trailer before you disconnect it from the truck, since the tongue may be the only thing holding it.

Put chocks on both sides of the same axle when you can, and chock the downhill side as a minimum. On a slope, place them on the side the machine would roll toward. Keep a few chocks in each tractor and truck so they are there when you need them.

If you must work with the engine running, such as when adjusting a hitch with the tractor backing slowly, have a second person watching and keep the tractor brake set as the manual permits. Remove the chocks only after the machine is hitched and ready to move, and say out loud that you are pulling them.

What makes a good chock?

Use chocks made for the job, sized for the tire and the weight. Rubber or heavy-duty plastic chocks with a good grip work well on most surfaces. Wood scraps, rocks and bricks can crack, slip or roll out of place, so skip them.

Check chocks for cracks and wear. On ice, mud or loose gravel, a chock can slide, so choose a firm surface or use chocks with a gripping base. Place them snugly against the tire tread, tight and square.

• Purpose-made chocks
• Sized for the tire
• Replace cracked or worn ones
• Firm footing, snug fit

How do you block a raised implement or tractor?

Use stands or cribbing that are rated for the load, set on firm, level ground. Check the manufacturer's manual for jacking and lifting points, since the wrong place can bend frames or slip. Use wide, stable bases, and place blocks before anyone goes under the load.

Stack cribbing in a crosshatch pattern with solid, undamaged timbers. Do not use cinder blocks, which can shatter under load, or stacked scrap of mixed sizes. Lower the load onto the supports and give it a gentle push to test that it is stable.

Check that the load stays on the stands as you work. If you hear creaking, see a tilt or feel movement, back away and lower the load before trying again. Never rely on a single stand when the manual calls for two.

What are the biggest mistakes?

The first is skipping blocks for a quick job. Most crushing injuries happen during short jobs. The second is using the wrong material, such as a cinder block or a rock. The third is working on soft ground, where a jack or stand sinks. A board under the base spreads the load but does not replace proper stands.

Another mistake is working alone with a heavy load. Let someone know where you are or have a helper nearby. Do not crawl under a machine that is held only by a jack.

• Skipping blocks on a quick job
• Wrong materials
• Soft or uneven ground
• Working alone under a load

What about loaders, three-point implements and rollover risk?

For front loaders, lower the bucket to the ground and keep it there, or use the manufacturer's loader stand or support if you must work beneath it. For three-point implements, lower to the ground or onto stands. For a tractor itself, blocks go under the frame at points the manual approves.

A tractor on a jack can shift and fall sideways, and a tractor tire with a loose lug nut is dangerous too. If the job is heavy, call a mechanic with proper lifting equipment.

A quick tip for any lifted job: keep your body out of the path the load would take if it fell, and keep your head and chest clear of the space under it. Check the stands again after any hard pulling or hammering, because vibration moves them.

More in Tractor Operation & Safety

• Lockout/Tagout for Farm Equipment
• Inspecting Work Areas Before Operating
• Safe Operation Near Power Lines
• Digging Safely with Equipment
• Trenching Safety Basics
• Avoiding Hydraulic Injection Injuries