UMS Gear Pump Belt Drive Conversion

[RCP57]

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

Thanks Reg

[Vanisle]

Originally Posted by RCP57

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).

[RCP57]

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