Handwheel Shaft Locking/Unlocking!

I didn't download the catalogue, but maybe.

http://www.lovejoy-inc.com/products/shaft-locking-devices.aspx

I'm familiar with Lovejoy couplings and they don't anything like I described. Thanks anyway. Judging by the overwhelming number of responses...it seems like I saw on a gearbox years ago must have been a custom device.

what you are describing is a brake or clutch unit. these can be had in all versions. electric pneumatic hydraulic and manual. search for gearbox brakes.

good luck

I see these things every day. They are a dog clutch used to engage and disengage the drive to the wheels on some brands of wheelchairs. You could source it as a spare part. Unfortunately the chair I know for sure it is on is an Australian made chair, where are you?

Jim

Check out a Gates Draughtguard™anti-rotation device @www.gates.com

Was intrigued and checked.

Would be Gates Draftguard: http://www.gates.com/news/index.cfm?id=11291&show=newsitem&location_id=752

Dog clutch!...that's what it looked like (that's the word that didn't occured to me). I found the picture below on practicalmachinist.com and it looked almost identical but served the oposite purpose. The picture below shows the clutch keyed to the shaft after the hand wheel. When it's pulled back (as shown) the hand wheel is what rotates freely. This arrangement does not lock the input shaft. The the clutch I saw was in between the hand wheel and the gearbox input shaft cover. The slots in the dog clutch engage onto the protuding socket head cap screw heads of the gearbox input shaft cover. Since the clutch is keyed to the input shaft, it prevented the shaft from rotating.

At least now I'm on the right track. Thanks for the tips. I'm still thinking the thing was custom because it was installed on a standard Boston Gear worm drive unit. Those don't have a long enough keyway or input shaft to allow the installation of a clutch like this. I wish I had a picture of it.

In this instance, if I remember correctly, the only reason the dog doesn't engage a shaft when it disengages the handle is because there is a separate clutch to engage the carriage leadscrew. The dog on the handle was only to release the handle so it wouldn't whack the operator in the hip after engaging the leadscrew.

Of course I can't remember the amount of times I forgot to disengage the handle and got whacked anyway!!

Hooker

At least you didn't get whacked by Uncle Vinny.

True, but I could've defended myself against Uncle Vinny. The lathe had unfair advantage!!

The previous item I suggested stops it reversing but does not lock it stationary. I don't know of a single proprietary item to achieve this but a shaft collar with one or more holes drilled into the edge, a latching 'indexing plunger '(Google for suppliers), and a bracket would be simple to construct.

Thanks for the suggestion. I've also used the handwheel itself with holes drilled radially.If the hub is long enough you can get away with it. The problem with these indexing plungers is that they are not very robust. I haven't found one yet that can stand up to reasonable abuse. I still use the arrangement for certain applications because it's simple but I was hoping to find a stock "dog clutch" type of component which is more robust.

Regards

The indexing holes can be positioned axially as well. A stronger, custom

made pin and a simple mechanism can privide a lot more shear section and

longer life. Contact info: www.tttool.com