5.3 Tools and Dowels to Identify Crush/Shear

Tools and dowels to identify crush/shear

Domain 1M is the procedure that matches the Domain 1L causes. CPSC 2025 §3.1 tells you that testing criteria for crush or shear hazards are found in ASTM F1487. The NRPA Table of Dimensions, Rev 1/2024, names the rods. Your job is to pick the correct diameter, put that rod in the accessible gap, and keep it there while the equipment moves. A photograph of a quiet gap is not a crush/shear test. A finger in a live joint is not a crush/shear test either.

The dowel / neoprene-rod method

F1487 crush/shear probes are specified-diameter neoprene rods (the common 0.62 in rod is explicitly a neoprene rod on the NRPA Table). Neoprene compresses slightly the way a finger does; a steel pin of the same diameter is not the published tool. The method is the same on every piece of moving equipment:

1. Identify the accessible gap that can close during a normal use cycle — under a spinning platform, at a seesaw fulcrum, between roller-slide rollers, at a hanger, between spring coils, under a trolley seat, at a gate hinge.
2. Select the equipment-specific rod from the table below. Do not default to 0.62 in on a merry-go-round or a roller slide.
3. Insert the rod into the gap in the orientation a finger or limb would take. If the rod cannot enter, that gap is smaller than the protected body part for that equipment — continue around the perimeter, because gaps change.
4. Keep the rod in the gap throughout the range of motion. A second person slowly cycles the equipment, or you lock/block the equipment at successive stations through the cycle if motion cannot be controlled. The question is not “does the gap look small at rest?” The question is “as these surfaces move, can they crush or shear the probe?”
5. Fail if the probe enters and can be crushed or sheared as the parts move — pinched, rolled, cut, or trapped between the surfaces. Pass that station if the rod never enters, or if it enters a space that does not close on it through the motion (and a more specific clearance rule, such as the 9 in rotating-equipment relief, is also met).

Those last three rows are not “other crush rods.” They are related dimensional checks that travel with the crush/shear kit because they protect the same body parts in motion. To-fro swing clearances are tested with a 13.1 in seated hip breadth (NRPA Table, F1487 8.6.5.1) so the occupied seat’s path — not the empty belt — is what you clear against the adjacent chain, the support, and the next seat. Seated trolley under-seat clearance is a 12 in minimum so a hanging foot or a child beneath the path is not crushed against the surfacing or a deck. Sliding-pole diameter is a 1.9 in maximum (F1487 8.4.4) so the pole remains a grip, not a torso-scale cylinder a child cannot release; it sits next to crush/shear tools on the table even though the failure mode is grip/entrapment geometry rather than a closing nip.

Walk the equipment the way a child uses it:

• Merry-go-round. Use the 0.30 in rod on platform openings and on the flush-deck-to-surfacing gap in any direction. Then measure underside clearance at several stations around the perimeter. Confirm a flush deck is ≤5/16 in, a skirted/raised deck is in the 2.38–3.5 in band or greater than 9 in without abrupt rigid members under the platform, and that the equipment has no up-and-down motion (CPSC §5.3.4).
• Seesaw. 0.62 in rod at the fulcrum through a full board cycle; check seat-to-ground crush at both ends; confirm the shock-absorbing tire or equivalent CPSC §5.3.5.1 called for is actually there.
• Roller slide. 0.19 in rod between adjacent rollers and at each roller end versus the rail, along the entire chute, including worn or missing rollers that have opened a nip.
• Swing hangers and spring rockers. 0.62 in rod in every accessible joint and coil through the motion; do not test only the rest position.
• Trolley. Tape the under-seat clearance to the 12 in minimum along the travel path, then use the 0.62 in rod on any moving hanger or trolley-to-track nip.

Never put a body part in a moving gap

A live crush/shear test uses the probe, not an inspector’s finger, not a child’s hand, and not a stuffed glove. F1487 and CPSC do not publish a “use your finger if you forgot the rod” allowance. Control the motion so the rod — not you — occupies the nip:

• Two-person method. One inspector holds and watches the probe. The second person slowly rotates, rocks, rolls, or rolls the trolley through the range of motion on command and stops the instant the first inspector calls. Agree on a stop word before the equipment moves.
• Lock or block method. When a second person is not available, or when the equipment is too energetic to hand-cycle safely, lock, pin, or block the equipment at successive stations through the cycle and insert the probe at each station. You must still cover the full range of motion; three rest-position photos are not a cycle.
• Out of service during the test. If children can reach the bay, bag it or stand a second adult as a barrier. A moving merry-go-round with a probe under the skirt is not a public demonstration.

If you cannot control the motion, you do not run a live test. Take the equipment out of service, document why the test could not be completed safely, and return with a second person. Guessing that “it looked like a 0.62 gap” is not Domain 1M.

What to write down

A crush/shear finding is useless if a third party cannot repeat it. Record, at minimum:

• Equipment type and identifier (merry-go-round, roller slide, south bay to-fro, seated trolley, etc.), including age group.
• Probe used (0.62 in neoprene, 0.30 in, 0.19 in) or the related dimension (13.1 in hip breadth, 12 in under-seat, 1.9 in pole).
• Location precise enough to re-find (“west quadrant, underside of deck to surfacing, 14 in inboard of the perimeter”; “roller 7 to roller 8, left rail”).
• Range of motion you applied (full rotation, one seesaw cycle, hanger arc from rest to 60 degrees, trolley from east landing to west landing).
• Result (enter / crush / pass), the cited F1487 or CPSC section, priority, and the interim control.

An accessible moving crush/shear that fails the published rod is Priority 1. The owner decides whether to close the gap, add a compliant skirt, raise the underside above 9 in, replace rollers, or remove the equipment. Domain 1M is the named probe, the named station, and the named motion that proves the Domain 1L cause is present.