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