View Full Version : Is there a special name for this coupling?

10-16-2006, 02:54 PM
As the subject says:

Is there a special name for this thing? Important characteristic is the 2-tooth arrangement and the fact that there is really no male/female type - both sides of such a coupler are the same. The shaft-to-bore can be several types (this one is splined), including keyways/setscrews and threaded. For reference, the OD of this coupler is 2.5", and the shaft is .75".


MSC has something similar called an "Oldham" coupling, but it has a plastic or rubber insert that goes between the metal bits. The one I'm looking for is a straight metal-to-metal interface.

Thanks in advance, folks.


10-16-2006, 03:05 PM
Oh, McMaster has something similar called a "spyder" coupling, but it also has the rubber or plastic spyder between the metal parts. I don't want the rubber or plastic - just the metal parts.


John Stevenson
10-16-2006, 03:12 PM
That looks like a spyder coupling that has lost it's insert.

No on looking again the space matches the male part, plus it has a groove in it for a selector fork.
Couplings are usually couplings and not engagable, [ is that a word ? ] it now looks to me like a propiatry part

10-16-2006, 03:15 PM
you can try using one with out the rubber bumper. It looks like a engage/disengage clutch at zero speed to match the teeth to interlockthe drive and rotating part.

10-16-2006, 03:22 PM
Is the splined shaft transmitting any power?

If not, then both faces being the same, driven directly, depending upon the lugs for power transmission....

Looks and sounds to me like a positive drive clutch.

10-16-2006, 03:25 PM
Thanks for the reply, Sir John. The photo is but one example, and that particular one is grooved for a selector fork. The others aren't.

I might as well provide more of the "why" here. This is the problem:



Note the horrendous wear on the coupling.

This is from something called and "Ariens" tractor. It looks like a snowblower, kind of. The difference is that the snowblower part separates from the engine and drive wheels, and you can fit other implements. These include a mower deck, a chipper/shreader, and a tiller.

Actually, Sir John, I am repairing these things using a trick I learned from you. I tried it out on a piece of rebar, and it worked for the test, anyway. I built up the worn (missing) material with the welder, then machine it down to the original shape. I took a .5" dia rebar, built it up with weld, and machined so it had a collar in the middle that was 1" in diameter. I remember you telling of repairing a motor armature this way. I believe the bearings had worn completely out, but the motor was kept running until the shaft was badly damaged. I was impressed with the results you got.

Well, the fix isn't all that hard, and it's for a good cause. (My boss.) I just have a funny feeling that this type of thing is readily available somewhere, and I'll have put $$$ worth of time and energy into a $ part.

As for transmitting power: yes. There's an 8hp motor on one side, and the "implement" on the other.


10-16-2006, 03:31 PM
That's a manufacturers specific part. It looks like some sort of sliding clutch arrangement. The two-prong part "looks" like a Love-Joy half but the collar on the back is part specific.

What's it go to and who is the mfg.?

kap pullen
10-16-2006, 03:54 PM
That looks like a DOG CLUTCH to me.

I have a couple on traction engines to connect and disconnect
the crank from the traction mechanism.

There is no space for an insert.

Here is a dog clutch discription I stole from out there somewhere.

"Dog clutch"

"The gear selector does not engage or disengage the actual gear teeth which are permanently meshed. Rather, the action of the gear selector is to lock one of the freely spinning gears to the shaft that runs through its hub. The shaft then spins together with that gear. The output shaft's speed relative to the countershaft is determined by the ratio of the two gears: the one permanently attached to the countershaft, and that gear's mate which is now locked to the output shaft.

Locking the output shaft with a gear is achieved by means of a dog clutch selector. The dog clutch is a sliding selector mechanism which is splined to the output shaft, meaning that its hub has teeth that fit into slots (splines) on the shaft, forcing it to rotate with that shaft. However, the splines allow the selector to move back and forth on the shaft, which happens when it is pushed by a selector fork that is linked to the gear lever. The fork does not rotate, so it is attached to a collar bearing on the selector. The selector is typically symmetric: it slides between two gears and has a synchromesh and teeth on each side in order to lock either gear to the shaft."


cam m
10-16-2006, 04:04 PM
What Kap said.

It is a dog clutch. The type you've shown here is the least forgiving design. They come in the style shown with square tooth profiles, with tapered or ramped teeth, or simply slide to bridge across two splined shafts. I've seen them on drilling rigs (older Emsco drawworks for speed changes and function selectors), farm equipment (NH mixer mills to engage/diengage unloading augers), and heavy winches (101,000# Tulsa? to allow a free spool option).


10-16-2006, 04:20 PM
As for transmitting power: yes. There's an 8hp motor on one side, and the "implement" on the other.-Mark

I took forgranted that it was assumed that I had meant the splined shaft transmitting power directly to the other half of the clutch. (ie. splined shaft passing through both halves, and powering the impliment.)

"I just have a funny feeling that this type of thing is readily available somewhere, and I'll have put $$$ worth of time and energy into a $ part."

Probably a very true statement.

10-17-2006, 02:10 AM
I would say an older version of a dog clutch,,Lovejoy,,Johnson coupling. Can't tell by the pic, but some were designed to rotate and "Grab" in only one direction, using a tapered section to grab and release, spring loaded. Very seldom.....but I could be wrong!

Forrest Addy
10-17-2006, 10:19 AM
Yup. It's called a jaw or Lovejoy coupling. They're common as salt in lower end eqipment where a compact direct drive from a motor or engine is called for. The mating piece is identical and when they're assenbled into position, an elastomeric element fits the largish clearance space between the jaws. They're low in cost and very reliable in driving load shafts even when not perfectly aligned. The elastomeric spider comes in a variety of materials selected for shock absorbtion, rigidity of drive, environment, etc.

Replacement couplings are available from Lovejoy and most any industrial supply catalog.

10-17-2006, 11:46 AM
It is a dog clutch, very common on silage and feeder wagons. Slow speed shafts, not a heavy load clutch.


10-17-2006, 12:46 PM
G&G of omaha mfgs those .
should be available from any TSC or Central Supply page 211 currant catalog 1800 444 8666.

Called flex coupling

I don't think it was suposed to be metal to metal.

10-17-2006, 04:12 PM
MSC has something similar called an "Oldham" coupling,

The Oldham coupling is for parallel shafts which aren't exactly aligned on the same axis. In other words, it accommodates parallel misalignment, but isn't as big and clunky as a Schmidt coupling, which uses two sets of three links to do the same job. Oldham has a center piece with rectangular lugs on each end, at right angles to each other. The lugs can slide in slots in the two end caps which are attached to the shafts. It's not much like the one in question. Good picture here -


10-17-2006, 05:43 PM
Hi Mark,

This is the same arrangement OMC uses in the lower unit of their older outboard engines. The clutch dog rides on the splined shaft and their is a shifting fork to engage forward and reverse gears by pushing the two toothed dog into recesses on the bevel gears that turn the prop shaft.

best regards,

10-17-2006, 09:19 PM
That is not a lovejoy type coupler although it is similar. It is not supposed to have a flexible insert between the two halves. This was a common type of clutch on older snow blowers.Usually it was used to disconnect power to an implement such as a blower or mower deck. There is usually a secondary means of engaging the implement such as a belt tensioner. This type of clutch is not designed to be engaged or disengaged while the input shaft is turning. I actually have a mower deck for the Ariens machine you have. unfortunately I don't have the traction unit to attach it to. New clutch halves will be readily available from a local Ariens dealer but what's the fun in replacing parts? Isn't more fun to weld up the worn parts and remachine them?