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Old 12-18-2011, 11:20 PM
Vanisle Vanisle is offline
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Default UMS Gear Pump Belt Drive Conversion

I finally made some time to work on a pump. I had an UMS pump that I wanted to convert to a belt drive. I have some other gears to try making my own pumps if this works out.

Here is what it looked like after I disassembled the UMS gear pump from the stock motor.




First I faced the back and then made a bronze stepped bushing. I then made a shaft from 1/4 inch stainless rod. I turned it down to 2.31mm to press fit into the 2.27mm hole (.0015 inch difference) of the gear. You can see a similar shaft and bushing in the photo but those are ones that didn’t work out. I also made an outside collar for the pump housing to give more room for bolt holes, press fit and three 3mm bolts to hold it secure.




Here is the bracket (made from 1x2 block - gotta love how much material a roughing endmill will remove) to hold the motor and gear pump.




Here is the gear pump assembled and bolted to the bracket.




Here is the pump shaft pulley (42t) - bearings on both ends.




And finally with the 800 KV motor (35-48) and drive shaft pulley (14t, I also have a 16t for use with a larger 42-50 size motor) installed. Both shafts are dimpled for the set screws.





All of the pieces



And my DRO (showing the bolt circle pattern program) that made it possible (well, that and my lathe and mill).



I hope to test it sometime this week.

Richard

Last edited by Vanisle; 12-18-2011 at 11:24 PM.
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Old 12-18-2011, 11:26 PM
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RCP57 RCP57 is offline
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Default Re: UMS Gear Pump Belt Drive Conversion

Looks good! Where did you get the pulleys and belt from?

Thanks Reg
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Old 12-19-2011, 12:07 AM
Vanisle Vanisle is offline
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Default Re: UMS Gear Pump Belt Drive Conversion

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Originally Posted by RCP57 View Post
Looks good! Where did you get the pulleys and belt from?

Thanks Reg
I don't remember for sure but I think i got them from McMaster. The belts are 70t MXL 1/4 wide. I have bunch of smaller pulleys in 1/8 and 1/4 size and different lengths of belts but this seemed to be a good starting point. One issue is the size of the motor shaft, the larger 42-50 motors have a 3/16 shaft so the 1/8 bore in the 14t is too small, you need to go up to a 16t to get a 3/16 bore. THe 35-48 motor had a 4mm bore so it was easy to bore out the 14t shaft on my lathe. Fortunately, the larger 42t pulley has a 1/4 bore so it just fits a 1/4 stainless rod.

If I recall, the smaller pulleys are about $9 each and the larger ones are about $12. The belts are only a couple of dollars.

I have a bunch of gears from SDP or maybe it was QTC gears (same owners I think) to try out to make my own gear pump. Maybe sometime over the holidays I will get a chance to build my own gear pump. I already made a second bracket (it doesn't take long with a roughing endmill).
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Old 12-19-2011, 12:43 AM
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Default Re: UMS Gear Pump Belt Drive Conversion

Thanks Richard, I was looking at Mcmaster's website a couple nights back and I saw the pulleys and belts there. How do you find them to order from? I wanted to order the nuts and bolts for my tracks from them but I wasn't sure if the shipping/customs would be too expensive.

We used a gerotor style set of gears to make a mock up pump for my Volvo but so far I've only driven it with a 2600rpm drill so I'm not sure if it will be too hard to turn for an RC size motor. It pumps around 1.2l with no load but only just over half at 25 bar through the relief valve so I'm not sure if that's OK or not? If it doesn't work out we will switch to an external gear pump like you are building.

I'd love to see one of those valves you have sometime

Reg
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Old 12-19-2011, 12:46 AM
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Default Re: UMS Gear Pump Belt Drive Conversion

Fantastic work Richard. looks like the new machines are working out well. I like the setup that you have and I think that will be a lot better that the direct drive. Will be real interested to see the results when you have it running.
Rob
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Old 12-19-2011, 01:30 AM
Vanisle Vanisle is offline
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Default Re: UMS Gear Pump Belt Drive Conversion

Reg,

McMaster is great to order from ... but I always get it shipped to my US mailing address. I get to Vancouvere every month or so and just go down and pick stuff up.

You can look at the valves anytime but I prefer not to post photos. You are welcome to check it out in person.

Rob,

Any idea why the belt drive is better than direct drive? I have thought of doing a direct drive too so it would be more compact.

Richard
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Old 12-19-2011, 09:32 AM
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Default Re: UMS Gear Pump Belt Drive Conversion

Maybe I could come and visit you between xmas and new years? I'd love to see your shop and your projects... who knows, maybe I could convince you to hurry up! JK

Thanks Reg
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Old 12-21-2011, 12:36 PM
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Default Re: UMS Gear Pump Belt Drive Conversion

Do you have a pressure relief valve in the pump or is it external? If it is in the pump can you show how it is made? Thanks.
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Old 12-21-2011, 02:16 PM
Vanisle Vanisle is offline
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Default Re: UMS Gear Pump Belt Drive Conversion

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Originally Posted by dirtpusher9 View Post
Do you have a pressure relief valve in the pump or is it external? If it is in the pump can you show how it is made? Thanks.
No, I have not built a pressure relief valve yet. I am still experimenting with the pump itself and am quite away from actually using one in pressurized system.
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Old 12-28-2011, 01:59 PM
Vanisle Vanisle is offline
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Default Re: UMS Gear Pump Belt Drive Conversion

I ended up stripping the inside of the drive gear so never got this going. I am not sure what the problem was but I think the original hole was slightly off center so it didnt quite line up with my lathe centered hole on the bronze bushing. I have been experimenting with some other gears I have but so far haven't had success (for other reasons). Defintely easier just to buy a pump but I am not quite ready to give up yet.
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