Coupling, with axial shaft movement

[GRW]

Drive Coupling Gear Pumps to Electric Motors

The drive coupling is used to connect the shaft of an electric motor to the shaft of a hydraulic pump.This range of hydraulic couplings are made from aluminium with a flexible rubber spyder. We stock a large range of couplings to suit most manufacturers pumps and most electric motors up to 270...

www.phoenixhydraulics.co.uk

A search on Google for Fenner Couplings or Flexible Drive Couplings brings up several. Perhaps thus might lead to identifying a suitable item

 

[addjunkie]

There are so many different types of coupling available. But time consuming studying the different ones till you find one that will fit.

what about something like this

Sure-Flex Shaft Coupling | ABSSAC

We stock the full range of Sure-Flex couplings as well as the full range of EPDM, Neoprene, or Hytrel sleeves. Sure-Flex elastomeric shaft couplings rely on a proven element produced from a elastic polymer, to compensate the shaft misalignments but also transmit torque whilst simultaneously...

www.abssac.co.uk

 

[dan.taylor.1]

3000 RPM is quite high for a typical PTO shaft.

Do you really need the 5-10mm travel?

It is, they're rated at 1k, I think due to the ujs, but often have 200hp going through them so I think a small electric motor will be fine.

 

[slim_boy_fat]

Could something like this be made to suit the OP's application?

 

[Sergei Slovenija]

Sounds a bit like what we'd call a Fenner Coupling perhaps?
Some old gensets have Fenner Couplings, joining an engine output shaft, to a Twin-Bearing Alternator input shaft.
The flexible Fenner Coupling does a similar job to above - in that it allows a small amount of movement.

 

[Sergei Slovenija]

Drive shaft with axial movement, has 4 bearings, 2 roller bearings and duplex ball bearings, on a length of 400 mm. Roller bearings have a custom inner sleeve, longer than the standard one (the shaft can slide relative to the rollers). We have a lot of support shaft with minimal runout at the end. In fact, a kind of analogue of the ICE clutch, but without breaking the torque from the electric motor.

 

[Sergei Slovenija]

The workmanship of the original coupling does not suit me. Grooves, semi-cylinder in cross section) are made by wire cutting (electroerosion) in a hardened crown. Wire traces are visible, therefore, polymer cylinders, with axial displacement of the shaft, gradually and unevenly wear out.

 

[m_c]

The issue is the continual movement.
Out of all the couplings suggested, I don't think any would handle that amount of movement for any great length of time, and the current option is probably a reasonable solution.

I'd also guess the coupling has been EDM'd for a reason. If the grooves were to be polished, the polymer is likely to suffer severe stiction, which underload could easily prevent the coupling from sliding.

 

[Sergei Slovenija]

.

I'd also guess the coupling has been EDM'd for a reason. If the grooves were to be polished, the polymer is likely to suffer severe stiction, which underload could easily prevent the coupling from sliding.

we use sticks made of oil-filled polyamide or polyacetal. There is no sticking.

 

[Morrisman]

Propshaft on my LDV Convoy has one fixed UJ, and the rear is on a sliding spline to allow for length changes with rear suspension travel

Same on many vehicles, slip joint in the back of the transmission with U/J on.

 

[mike os]

Could something like this be made to suit the OP's application?
View attachment 383541

Beam couplings won't handle that end float

 

[Screwdriver]

I have always wanted to make a Schmidt coupling.

But I have never had the need for one...

 

[Gareth J]

Torque when being asked to slide/move is important. Current setup could be worse!

 

[wyn]

I think a few people might have put up links for "Tyre couplings"

No moving parts just the tyre flexing. And i think the larger the coupling diameter, the more axial misaglignment they can take. Should get one for 3000rpm and 5Kw.

 

[Erie Fred]

I think a few people might have put up links for "Tyre couplings"

No moving parts just the tyre flexing. And i think the larger the coupling diameter, the more axial misaglignment they can take. Should get one for 3000rpm and 5Kw.

Like Dis' ?

https://www.rexnord.com/products-services/process-motion-control/couplings/elastomeric-couplings/omega-elastomeric-couplings

 

[wyn]

Like Dis' ?

https://www.rexnord.com/products-services/process-motion-control/couplings/elastomeric-couplings/omega-elastomeric-couplings

Yes. That sort of thing.

 

[m_c]

we use sticks made of oil-filled polyamide or polyacetal. There is no sticking.

There will be no sticking because the surface is rough. Polymer bushings require a certain roughness to run on.
If you were to polish the surface, you run the risk of the polymer sticking to the surface and you then face two potential problems.
The sticking could result in the axial forces being transferred between the two shafts (given the setup, it could result in destroying the motor bearings), and the sticking can lead to the polymer bushing pulling itself apart, as it can essentially glue itself to a smooth surface.

If you want to read more about it, the Igus catalogue covers suitable shaft surfaces in reasonable detail.

 

[m_c]

Like Dis' ?

https://www.rexnord.com/products-services/process-motion-control/couplings/elastomeric-couplings/omega-elastomeric-couplings

It's not axial misalignment that's the problem, it's axial movement.
I did have a look at that catalogue, but I can't see anything about allowable axial movement, just the specs for misalignment.

It does appear to be a setup where I don't think there is going to be a simple option to make it more durable.
Splined shafts are likely to just wear out.
I'd suspect rubber/PU setups will eventually disintegrate, and 10mm of movement is going to put a lot of thrust force through the bearings.

 

[tom2207]

Wrote a post, already falling asleep. Details: electric motor 5 kW + actuator, the shaft of which is moved by >5 mm by a pneumatic drive. A complex structure where the shaft passes inside the pneumatic cylinder. Operating mode: turned on in the morning, turned off in the evening. I don't like the existing solution. If you use a spline connection + cardan - there will not be enough space, IMHO. The old coupling is made in the form of plastic cylinders placed in a circle in the depressions (grooves in the crown, in the form of a half-cylinder) and a reciprocal steel ring with grooves + end caps. Noisy device, polymer elements wear out over time. Compensates for slight shaft misalignment.

View attachment 383536

little more than a cush drive really . They ue a similar set up when driving hydraulic pumps in powerpacks.

 

[Sergei Slovenija]

There will be no sticking because the surface is rough. Polymer bushings require a certain roughness to run on.
If you were to polish the surface, you run the risk of the polymer sticking to the surface and you then face two potential problems.
The sticking could result in the axial forces being transferred between the two shafts (given the setup, it could result in destroying the motor bearings), and the sticking can lead to the polymer bushing pulling itself apart, as it can essentially glue itself to a smooth surface.

If you want to read more about it, the Igus catalogue covers suitable shaft surfaces in reasonable detail.

In short, I disagree with this version. This coupling is made in a piece version, with a low level of applied technology. The discovery that it is possible for polyamide and polyacetal to adhere to steel simply by applying intermittent pressure is rewarded.