A spider is a boom on rubber tracks that sets itself on four legs before the boom moves, so its working weight lands on pads rather than on tires. That is what lets a machine reaching fifty to ninety feet stand on a paved courtyard, a lawn or an interior slab. Rates commonly run $500 to $1,100 a day, and the machines are scarce.
Why the legs are the whole design
The tracks only drive it into position. Once there, four independently adjustable outriggers lift the frame, level it on a slope and take the load. That is the reason a compact machine can carry a long boom safely, and also the reason siting one badly is the failure mode rather than driving it badly.
Reach from a standing start
Because the base does not move once set, the reach envelope has to cover every part of the work from one position. Yards quote working height and maximum outreach separately, and the outreach shrinks as the platform rises. Mark on a plan where the machine can stand and check the furthest point of the job falls inside both figures.
What the ground under each pad has to carry
The frame's weight concentrates on four small feet, so the pressure under a pad is far higher than the machine's overall weight suggests. On block paving, a suspended slab, a basement lid or a lawn, that means spreader pads and often a structural opinion. Ask the yard for the outrigger loading figure and hand it to whoever owns the surface.
Lead time, not price, is the real constraint
Spiders are specialist stock. Of the 5,830 rental establishments the Census counts across 544 counties, only a small share hold one, and those are concentrated near cities with glazing, atrium and heritage work. Start the search two weeks out and be ready for haulage from further away than usual.
Questions people ask about spider boom lift
Will a spider boom fit through a doorway?
The narrow models are built to pass a standard double door with the boom stowed and the legs folded, commonly around thirty inches wide. Measure the tightest point of the whole route, including any turn, and give the yard that number rather than the door width alone.
Can it be driven while the platform is raised?
No. On outriggers it is a stationary machine, and the boom must be stowed and the legs retracted before the tracks move again. Moving to a second position costs setup time, which is why the standing position is chosen on paper first.
Is it cheaper than a conventional boom lift?
No, it is usually two to three times the rate of a similar reach on wheels. What it buys is access to places a wheeled machine cannot go at all, so the fair comparison is against scaffold, a crane and platform, or losing the job.