A question that came up in a couple of rigging / safety forums recently: Have you ever witnessed a chain hoist brake fail catastrophically? It came up in discussions about the need and suitability of double brake hoist hoists. Also raised an interesting side line: How do you know that the first brake hasn't failed and you are actually running on your second brake thus making it a single brake hoist? I am not a rigger but interested from a risk management perspective.
I can not ever recall a chain hoist failing. One thing I have seen reported twice over the years in the company I work for is a failure in the roller carrier that is running on an I beam in which the hoist is hanging from. When they are assemblied on the beam the wheels and spacers have to go on in the correct orientation. What looks correct is usually backwards. We have a program for checking roller carriers before use and we have had a number of them come to the job assemblied wrong from the rigging equipment rental yards. The worst one was a six hundred horse electric motor that was being replaced on an emergency basis and one carrier broke overloading the pick and dropping the motor 40 ft. Lucky the area was properly secured and no one got hurt but the piggy bank took a big hit. The small carriers as well as the large ones are often assemblied wrong when placed on the beam.
I've beaten the **** out of a few 1500kg hoists. Way over loaded, abused etc. usual site work and then some. Bent hooks, sheared links, never had a brake fail tho. Only small stuff I know but it does raise an interesting question. So should you raise this with your h&s officer or not? Safety tackle when using a chain ratchet or hoist just wouldn't work!
I have known of only one, but it was abused beyond the point of the ridiculous. A local (idiot) fellow had a 1/2 ton chinese cheapo hanging off of a piece of pipe on the tail of a c10 Chevy as a home made wrecker. He mostly hauled scrap with it. He would pick up the nose of one car and set it on the trunk lid of another, then lift the nose of the bottom car with this poor hoist and tow it down the highway on the hoist's brakes. After doing this for a while, he added a third car. When he hit the railroad tracks, the brake grenaded. He continued to use the hoist to lift the cars, but had to add a chain to hold them up, since if you let go, the load fell. So, in short, if you act only mildly senseless, I don't think there is a great risk of it.
I think it would be akin to the risk of a brake failure on an automobile, always a possibility, but no real way of doing an adequate assesment without causing further damage.
I've never had the friction brake fail itself . Have had the ratchet pawl stick open on a few hoists allowing them to freewheel backwards . Pull the covers off & lube them up from time to time will fix that . Another thing I do is tie the hand chain in a knot in case something went wrong with the brake to keep it from freewheeling down at a bad time . I like chain hoists , use them all the time . Used 9 of them on this job http://www.heavytruckforums.com/showthread.php?51-Fwd-Trucks&p=1251&viewfull=1#post1251
I bought a 1 ton budgit off craigslist a few years ago. One of the friction disks had soaked up oil and disintegrated, I could see that happening at an inopportune time.
The bolt looseness will cause the failure of hoist brakes failing. Monorail hoists