I need a safety "clutch" for a dog lift

[fatkatie]

I built a dog lift that takes him up a very long flight of stairs. The platform uses a $150 AC powered winch that has forward and reverse. It works well.
If the winch fails or the cable breaks I'd like something to stop it from plunging to the bottom of the stairs.

The seat belt in my car allows me to slowly extract the webbing. I pull to fast and it grabs and stops. I'd like rig up something like that.
The "clutch" has to stop a 200# load and have a cable length of 18 feet. Any ideas?

[Troy]

FatKatie,

Can you upload some pictures so we can visualize it?

Fascinating project!

[fatkatie]

[fatkatie]

Part two of this is cable "slip". It causes the platform to drop and creates a shock. I need to install some shock absorber of some kind. The drop freaked out the dog. Now it takes hotdog bits to get him on it. The cable slip is caused by the cable not wrapping properly.

[handyandy]

You have the winch for the lift, but could you also attach an automatic locking retractor as well? You can buy seat belt parts, I think you could find the part you need.

[mrcaptainbob]

You're on to something here. I like it. The cable will never be a steady situation, however. This would take a bit more, but...I'd do a bicycle chain type thing. Maybe a bicycle sprocket riding a single strand along with an idler, spring loaded sprocket to keep tension on the drive sprocket. The motor's own action of on/off may be enough to 'brake' it. I suspect the motor has a bit of slow down in rpm's from power-on to power-off? May be just enough to keep it from' bumping...
The chain could be in a trough of some sort beside one of the 2x4 tracks... and rise up on some rollers inside the box where the drive motor is.
Another possibility is to do similar to a garage door opener. Mount the motor at the bottom of the stairs and wind a chain loop to the doggy carrier...
Sometimes crag's list has used garage door openers offered on the cheap...