Terratrac GT30 Next Question: Reservoir Size?

[Iplayfarmer]

I know that this has been discussed, but hopefully it's okay to revisit with some fresh perspective.

I'm designing the new hydraulic system on my Terratrac GT30 crawler, and I've come up with reservoir sizing question. The original design of my Terratrac GT30 loader hydraulics included using the loader frame as the reservoir. A little calculation of the volume inside approximately 20 feet of 2" pipe gives me 2.9 gallons. My new pump is rated for 6.6 to 9.9 GPM.

It seems like the prevailing advice on hydraulic tanks/reservoirs is to size the tank 2-3X the GPM capacity of the pump. *** HOWEVER *** I don't think that many of these little tractors with 11 GPM pumps are wearing 33 gallon reservoirs.

In a real-world, practical sense does the reservoir really need to be that big??

 

[ptsg]

No, it doesn't need to be that big.

I'll give you the example of my homemade backhoe.

I run a 11 GPM @ 2500 RPM pump for the main drive and backhoe and another 4 GPM for the thumb, flail mower and hydraulic auger.

That makes a 15 GPM system and the tank only holds 9 or 10 gallons of fluid.

Just moving and operating the backhoe, like digging a trench or something, the fluid never gets above 105F. The only time it goes a bit more crazy, is when I'm running the flail mower, since it's constantly under load. It goes as high as 160F but then I turn on the fans on the oil cooler to bring it down to 120F or so, but that's the only time the cooler gets used.

 

[Iplayfarmer]

Thanks ptsg. Your mention of the cooler is a good reminder. I was wondering if using the loader frame pipes as a reservoir would have a bit of a cooler-type effect on the oil (I.e. more surface area than a cubical tank). I actually have an oil cooler available on the reel mower that's donating many of the parts for this build. I'm debating if it's worth mounting it somewhere.

The other factor you brought up that makes some sense is that there's a difference between intermittent operation of a loader vs. continuous operation of something motor driven. I guess it ultimately depends on the operating temperature of the oil. I won't know if it's wrong until I get the project done and use the beast.

 

[ptsg]

Since you have the possibility of adding a cooler if necessary, you can proceed by making the tank with enough capacity for the cylinders and hoses.

You mentioned that's close to 3 gal. I would probably make a tank that could handle 4 or 5 gallons, maybe more.

Then, if you ever notice your hydraulics getting too hot, you can always add the cooler but I don't think you'll ever have any temperature issues.

The first loader I made, was for a small Kubota B7000. It had two double acting cylinders for the lift and a single double acting cylinder for the bucket.

The reservoir was one of the loader frame pump (thick wall square tubing) and if I remember correctly, it would only about 0.5 gal after all the circuit was filled but the loader always worked flawlessly and never ran out of oil at max height.

 

[Iplayfarmer]

Thanks, ptsg. You've given me a level of comfort that I can maybe make the existing loader frame work. At this point I think the progression will be to use the loader frame then add additional tank capacity if needed. Then, add the oil cooler if it ever comes to that.

 

[ptsg]

Sounds like a good plan to me! Good luck. :thumbsup:

Looking forward to see more progress on the restoration of this tractor.