(mechanical) Engineers of Oppo; What am I looking for?

"JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t" (jawzx2)
07/24/2018 at 12:55 • Filed to: None

So, I have a project where I envision a certain kind of self-disconnecting lever/ratchet, one that engages when moved, but is disconnected when “floating” in the center position. I can think of a method to do this with a split arm, cam, a spring-loaded pin and a corresponding hole track... but I can’t be the first person who has though this sort of mechanism would be useful, there must be commercial versions already out there. I shouldn’t have to reinvent the wheel when I could buy and off-the-shelf component to solve my problem.... except I have googled every name idea I can come up with for what this would be called and can’t find anything... I must just be calling it the wrong thing?

Basically I’m looking for what amounts to a bi-directional overrunning clutch (something I DID find) but in a low-speed, limited range of movement, ratchet/lever system. The lever should be disconnected from the device to be moved (in my case a push-pull cable system) when in the centered position, but when moved off of the center position it should engage the mechanism and move it, when released it should return to the “floating” center position without taking the device with it. Essentially this would allow ratcheting movement of the target device in either direction, AS WELL as allowing the device to move freely when the lever is in the floating position.

What would such a device be called?

I would even be willing to entertain a manual engagement system, where a button on the lever has to be pressed, or a collar lifted or something, the important bit is the floating/disconnected when not in use function.

DISCUSSION (11)

Party-vi > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t
07/24/2018 at 13:14

Ah, that would be a dickfer.

JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t > Party-vi
07/24/2018 at 13:19

I what’s a dickfer, I need a whoosit, or maybe a whatsamabob?

RamblinRover Luxury-Yacht > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t
07/24/2018 at 13:29

Sounds like your easiest bet would be to get one of several older types of self-locking 4WD hubs. Will lock up when the center axle (you’d connect to the lever) is turned forward or backward, will disengage when run the opposite way. The only tricky thing is that it’s hard to make release under load because the “handshake” (torque out, being resisted by the output) is still active, in reverse.

JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t > RamblinRover Luxury-Yacht
07/24/2018 at 13:46

I looked into that actually, self-locking hubs came up in my google searching, but they are mechanically large compared to what I was hoping for, and as you say the reverse-torque-out could be an issue... I might be able to work with it, but I just feel like there has to have been a use for what I envision in the past and such a mechanism must exist already that closely matches my intended use. S uch hubs also have vastly higher load capability than I need, and are not particularly cheap.

JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t
07/24/2018 at 13:52

*know what’s a dickfer...

MasterMario - Keeper of the V8s > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t
07/24/2018 at 13:55

It’s actually a thingamajig.

RamblinRover Luxury-Yacht > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t
07/24/2018 at 14:02

Well, I did have one more idea - something I’ve actually made use of myself. F orgot about it completely, but I built a two-way two-wheel bike axle thing using this trick . If you buy an older bicycle with a coaster brake, it actually has a two-way sprag setup in the rear hub. I think it’s a ramped brass cone one way and angled rollers the other, usually? whatever. The only thing to remember is that in one direction it locks the *axle* as well as the hub. One way only. If you support that on a bearing it’s not a problem, and you have a setup that locks from the “sprocket” drive going both directions with a center freewheel position.

RamblinRover Luxury-Yacht > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t
07/24/2018 at 14:06

One other idea I had, you could use a tailpipe expander.

Kinja'd!!!

The cones on the ends are cammed with steps so that you can expand a pipe incrementally, but what that also means is that there is a neutral position that turning it either way *expands* *from*. Locking up.

JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t > RamblinRover Luxury-Yacht
07/24/2018 at 14:15

hmmm..... I have a coaster brake I could cannibalize.... that might just work!

RamblinRover Luxury-Yacht > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t
07/24/2018 at 14:19

If you use a coaster brake, just remember that the engagement feel will be different going the two different directions, because the engagement works differently.

TorqueToYield > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t
07/24/2018 at 16:00

Y ou could potentially jury -rig something with 2 bicycle freewheels, one for each direction.