Jacking, Skidding & Rolling Heavy Loads
Machinery movers, millwrights and riggers often shift heavy equipment by jacking it up, sliding it on skids or rolling it on rollers. These methods work without a crane, but loads that slip off jacks, topple or roll away crush people. Weight, balance, solid support and a clear escape path decide whether the move is safe.
- Riggers
- Millwrights
- Machinery Movers
- Maintenance Crews
Methods
- Jacking: hydraulic bottle jacks, toe jacks, screw jacks, jack stands and jacking systems that raise the load so skids or rollers can be placed under it.
- Skidding: sliding the load on steel skid plates or tracks with a low-friction surface, pulled with a come-along, winch or hydraulic pusher. See Chain Hoists & Come-Alongs.
- Rolling: using pipe rollers, machinery dollies, air skates or Hilman-type roller dollies.
- Gantries and A-frames: structural frames with a hoist for lifting loads without a crane. See Rigging Basics.
Main hazards
- Load slips off a jack or falls when a jack kicks out, lacks a stable base, or the load shifts.
- Crushing between the load and the floor, a wall or other equipment.
- Tip-over of tall or top-heavy equipment due to a high center of gravity.
- Runaway loads that roll or slide on slopes or uneven floors.
- Hydraulic failure and overloaded jacks. See Hydraulic Hazards.
- Floor failure: concentrated loads can crack slabs and break through floors, pits or trench covers.
- Pinched hands and feet when placing cribbing and rollers.
- Strain injuries from pushing, pulling and prying. See Lifting & Ergonomics.
Planning the move
- Find the true weight and center of gravity from drawings, nameplates or a weigh. Do not guess. See Estimating Load Weight.
- Check the floor or ground capacity along the whole path and at lifting points, and plan for plates or mats to spread the load. Watch for pits, drains and utilities.
- Pick jacks, skids, rollers and pulling devices rated for the load with a safety factor, and inspect them. Jacks must have a stable, flat base and a locking or load-holding feature.
- Plan the route, turns, slopes, doors and clearances, and keep people out of the path. Remove obstacles.
- Make a step-by-step plan and hold a briefing, with one person directing.
Safe jacking, skidding and rolling
- Never get under a load supported only by a jack. Lift in small increments and block or crib the load as you go with solid cribbing or stands, keeping blocking just below the load. Lower the load onto blocks before working under it.
- Use cribbing that is dry, sound and stacked in a stable pattern (box crib), with no more height than the safe ratio. See Blocking & Cribbing.
- Place jacks on load-spreading plates and at the manufacturer's lifting points. Keep jacks vertical and loaded in line. Don't extend a jack to its limit.
- When using several jacks, lift evenly and in sync to prevent twisting or load shift. Watch levels.
- When skidding, keep the load low, pull slowly with controlled devices, use stops and chocks, and keep people to the side, not in line with the pulling cable or in front of the load.
- When rolling, keep rollers aligned, use steering lines, and have helpers place rollers with tools instead of hands. Never push on a load from the downhill side.
- Keep clear of the path, never stand where a load could tip or roll onto you, and have an escape route. Use tag or steering lines on tall loads.
- Stop if anything looks unstable. Re-block, re-balance and re-plan before continuing.
Heavy load moving checklist
- I know the weight, center of gravity and floor capacity
- Jacks, skids and rollers are rated, inspected and on stable plates
- The load is blocked or cribbed as it is raised; nobody is under a jack-only load
- Jacks are lifted together and the route is clear
- Nobody stands in the path of a tip, roll or pulling line
Standards & references
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