Pony Motor Question - 25 HP RPC

Balvar24 · Feb 25, 2020

As part of a deal on a compressor, I picked up the phase converter that the guy had. I've gone thru the sticky and come up with a wiring diagram I like, but still have a pony motor question.

Are you guys letting your pony motors spin after starting? That is to say - driven by the idler?

Does this cause a problem with a charge building in the run capacitor?

Thanks.

JST · Feb 26, 2020

Interesting point....

I think run caps are too small to cause an issue even if the motor had residual magnetism and could excite via the cap, but I think most mechanically disconnect the pony. .

Balvar24 · Feb 26, 2020

Thanks. The guy that I got all this from had the pony set up to spin continuously. The pony I got from him is a farm duty and the bearings don't sound so good. The idler on the other hand, is a cast iron beast.

I just need to come up with a cheap enclosure and some contactors now. The previous owner was doing everything with light switches and breakers.

thermite · Feb 26, 2020

Balvar24 said:
Thanks. The guy that I got all this from had the pony set up to spin continuously. The pony I got from him is a farm duty and the bearings don't sound so good. The idler on the other hand, is a cast iron beast.

I just need to come up with a cheap enclosure and some contactors now. The previous owner was doing everything with light switches and breakers.

You don't ordinarily save enough MONEY off the use of "band aid" class electricals to actually MATTER over a typical ten to forty year working life of an RPC.

Pay at least nominal attention to NFPA-70, the National Electrical Code, with use of decent goods, "New, Old Stock", used but good, or brand-new, "bought smart".

Power involved with a 20 HP RPC is a tad less "casual" than the average shop-vac or a phone-charger wall-wart, yah?

Give it what it deserves if you want "wire and forget" trouble-free daily USE thereafter.

Page Two:

One of the "easier" clutch/de-clutch srrangements is to use friction rollers insted of a belt.

Pallet-jack/stacker/hand truck wheels with their resilient tires, swing-plate mount for the pony.

Step on a treadle, a switch fires-up the idler, swing action puts the drive wheels to turning the idler.

Once wound-up, flip the contactor. Wired as a "motor starter" recommended so it drops-out if there is a power outage.

Off the treadle, pony motor is disengaged, switched-off, coasts-down.

rons · Feb 27, 2020

Balvar24 said:
Are you guys letting your pony motors spin after starting? That is to say - driven by the idler?

Design a system that will disengage the pony. RC airplanes are started with a motor that spins the nose cone until the engine starts.

Another method courtesy of J.R. to detach the belt.

Dan from Oakland · Feb 29, 2020

Had one that spun the pony motor for 20 years and it still works just fine in the old shop building.

Balvar24 · Apr 22, 2020

Replaced the bearings in my Pony Motor. Managed to get a contactor for the idler motor. Now I need to find a suitable enclosure on the cheap.

Froneck · Apr 22, 2020

You can get one way bearings, in that it's a bearing that will spin in one direction only and will lock if spun in the opposite direction. I worked in a company that had a machine that had a huge 3600 RPM motor 200HP. Yes we had 3 phase! Entire company Power consumption cost was near $300.000.00/month. However it had a 5 HP motor belted to it thru a one way bearing. It acted as a soft start for the large motor and a jog to use to clean the machine when the high HP was not required. When the 200HP was power-uped and power removed from the 5HP the belt driven pulley stopped spinning completely. Later when building large RPCs for friends using a pony motor I did the same thing especially when using a single phase pony.
I get quite a bit of cheap electrical items from HGR, they have a few cheap contactors Used Machinery & Industrial Equipment | HGR Industrial Surplus
Sometimes I was able to buy a complete enclosure with contactor, transformer and various switches mounted for less than a single push button switch cost new. They are quite a bit distant from you but they will ship however their packaging cost seems a little pricey to me. Don't hurt to ask though!

thermite · Apr 22, 2020

Balvar24 said:
Replaced the bearings in my Pony Motor. Managed to get a contactor for the idler motor. Now I need to find a suitable enclosure on the cheap.

I'm lazy and "cheap" all in one.

Bought a square expanded-metal file box and a round expanded-metal mesh wastebasket off scratch and dent bargain wall at Office Depot and straightened out the dents. "Mostly", anyway.

They pass cooling air REALLY well!

Not a lot of strength to them, but good enough to keeps rodents, hands, clothing, and such away from exposed spinning shafts of the idler motors!

Really, all yah need is a length of DWV PVC pipe on a flange, clear of the shaft, but long enough it is no longer "exposed".

That way, yah can even "cap" the end of it, since cooling air is dealt with at the other end for open, drop-proof, fan-over, or fan-through idler motors and TENV don't much give a damn, regardless - so long as yah don't throw a horse-blanket over 'em.

MichaelP · Apr 22, 2020

thermite said:
I'm lazy and "cheap" all in one.

Bought a square expanded-metal file box and a round expanded-metal mesh wastebasket off scratch and dent bargain wall at Office Depot and straightened out the dents. "Mostly", anyway.

They pass cooling air REALLY well!

Not a lot of strength to them, but good enough to keeps rodents, hands, clothing, and such away from exposed spinning shafts of the idler motors!

Really, all yah need is a length of DWV PVC pipe on a flange, clear of the shaft, but long enough it is no longer "exposed".

That way, yah can even "cap" the end of it, since cooling air is dealt with at the other end for open, drop-proof, fan-over, or fan-through idler motors and TENV don't much give a damn, regardless - so long as yah don't throw a horse-blanket over 'em.

I think the OP meant a control panel enclosure.

thermite · Apr 22, 2020

MichaelP said:
I think the OP meant a control panel enclosure.

Posted elsewhere on PM arredy.

NEMA from Hubbell Wiegemann.

Wiegmann | Hubbell Wiegmann

I buy mine through "Zorro". Listings are all over ebay as well.

Immediate ship, and better value-for-money than Hoffman.

I use the "WK" suffix for Without Knockout.

Got plenty of drills, annular cutters, hole saws, recip says, shears and nibblers here.

Generally don't NEED much in the way of holes, so they end up neater and easier to keep clean that way.

Balvar24 · Apr 25, 2020

I found a 14x16x6 with some pushbuttons installed for $30.

Can I pull from my idler contactor to my load rather than wiring from the idler?

pianoman8t8 · Apr 29, 2020

No, when I ran pony motors, I had a loose belt with a hand-operated tensioner. Kick on pony motor, pull tensioner, switch on power to RPC, then kill pony motor and release belt.

Balvar24 · May 20, 2020

I found a really good article that everyone should read interested in building/wiring one of these.

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=6977&context=rtd

Phil in Montana · May 20, 2020

That probably the best article I have read on a rpc...Phil

JST · May 21, 2020

It is rather good. A little light on the actual theory of operation, but otherwise good.

jim rozen · May 21, 2020

PhD thesis, Ames, Iowa - 1974

Phil in Montana · May 21, 2020

The author was a agricultural major not a EE, he did a dam fine job...Phil

Strostkovy · May 25, 2020

Just leave the pony connected and measure the charge on the caps/windings if that is your concern.

Or just leave the pony powered and measure the amperage.

thermite · May 26, 2020

Phil in Montana said:
The author was a agricultural major not a EE, he did a dam fine job...Phil

Yah well.. "Agriculture". That's to do with farming, right?

Whom else has to know a good deal about a whole buncha stuff.. or fail at "farming"?

Major, later Major General, Dayton Willis Eddy to Douglas MacArthur as he tried to keep communications for "GHQ South Pacific" up and running on whatever the Hell gear could be scrounged, built, modified, or outright stolen, whilst island-hoping towards Tokyo:

"General, I don't NEED any more G-dam "Degreed Engineers". What I NEED is a few more Iowa farm boys!"

Pony Motor Question - 25 HP RPC

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