Proof Testing

The following five tests where performed on a proof testing sled nicknamed the “Wilburnator” capable of pulling up to 44,000 pounds and recording test data via specialized software. This machine is owned and operated by B/A Products in Columbia, Maryland. A special thanks to Fritz for his assistance and technical expertise in completing these tests.

These first pictures are of the Crosby National CN-22 Flatbed Tester, and the samples to be tested. The gray test plate is made from 1/2″ thick A36 steel, and the green plates are #10 gauge (0.1345″) mild steel sheet to simulate the average thickness of a FEL bucket used on a small tractor.

The first test was a BOCM (bolt on clevis mount), bolted directly to the 1/2″ test plate with the same grade #8 bolts we include. A 1/2″ SPS (screw pin shackle) was used as well as other hardware to attach it to the test bed. As the machine pulled, the 1/2″ SPS was stretched and elongated, the big surprise was the 1/2″ thick test plate was bent as well! Finally at 21,753lbs the bolts gave up.

The second test was a BOGH (bolt on grab hook), bolted directly to the 1/2″ test plate with the same grade #8 bolts we include. The chain is 5/16″ Grade 70 (unplated) looped in a basket configuration for a equalized pull. The bolts did not break, but they were bent slightly. The 1/4″ base plate was deformed, and the chain finally broke at 19,885lbs.

The third test was a BOGH bolted to the 10 gauge (0.1345″) test plate, NO 1/4″ backing plate was used-only the four washers we normally supply with the hooks. The chain is 5/16″ Grade 70 (unplated) looped in a basket configuration for a equalized pull. Note that while the holes did elongate slightly, there was no evidence of pulling through the thin plate. The chain finally broke at 20,086lbs.

The fourth test is much like the third, except this time a backing plate IS used. The BOGH is bolted to the 10 gauge (0.1345″) test plate and backed up with a 1/4″ backing plate that we sell as an option. The chain is 5/16″ Grade 70 (unplated) looped in a basket configuration again for a equalized pull. From the top side, you won’t see much difference from test #3, the base plate is bent upwards almost identical. The bottom view however shows how the backing plate bent from the 10 gauge plate pulling it over. The chain finally broke at 19,113lbs, that’s 973 pounds less than without a backing plate interestingly enough.

The fifth test was very surprising. We bolted a BOGH to a 10 gauge (0.1345″) test plate with no backing plate, much the same as we did in test #3. Again, 5/16″ Grade 70 (unplated) chain was used, but this time only one leg of the chain was pulled to create a slightly off-center pull, this is how we use the hooks most of the time. As the machine pulled, the hook went near vertical, then the hook started to open as the links where almost pulled through and the chain slipped off at 12,240lbs. You can see the opened hook and bent chain link in the picture below.