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Cooler for hydraulics?

snowbird

New member
My SV200 didn't have hydraulics on it when I got it. I added a homemade system and I'm wondering if it needs some sort of way to cool the oil? I'm attaching a picture of the reservoir. The oil seemed to get pretty warm the other day when I tried grooming a trail for the first time.
 

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the standard hydraulics on the SV did not have a cooler but keeping them cooler is always better. open center valves? vane or gear pump ? gear pumps always create more heat, you may be picking up some heat from the exhaust there also .
 
Even a transmission cooler located above the tank would help take away heat. While a fan is nice just the airflow around the cab will take a lot of heat off the system.
 
i ill aggree with boggie cool is good you you appear to have a good sized resivoir so a cooler may be unneccessary but it wouldnt hurt and your oil should be quite warm but not scalding hot .if you are just using the hydraulics todrop your drag and are not useing them all the time look into a dry valve or a clutch to shut the system down and not build hest through the relief system
 
In addition to the good points others have made, if you do install a cooler be sure that your cooler is installed in a low pressure part of the circuit like on the return line to the tank. Nice hydraulic coolers, like those made by Hayden for instance, are rated at a few 100 psi, whereas automotive transmission oil coolers may be rated at less than 100 psi. Install a pressure relief valve rated to the cooler's operating psi upstream of the cooler.

A couple of extra things to consider given that we use our machines in the cold. What's normally a low pressure hydraulic line can have substantially elevated pressure before the oil is warm. This is because the oils have a greater resistance to flow when cold. The resistance to flow results in higher pressure in the lines, and you can burst things like coolers...even in "low pressure circuits. Trust me on this one. Along these lines, we want the oils to heat up to operating Tº as quickly as possible. A cooler is working against us here. Install a mechanical thermostat upstream of the cooler that bypasses the unit when the oil is cold.

Also, be aware of the operating Tº of whatever hydraulic fluid that you are using by reading the data sheet. Design a system to stay below the upper limit so the oil doesn't break down and cause damage to components. You likely won't have to worry about this unless you are really cranking away with high-flow attachments or hydrostatic drive.

If you are just adding hydraulics to operate some lift cylinders for intermittent use, I would bet that you won't need a cooler. There are formulas for reservoir design that can calculate it's cooling capacity. The main factors to consider here are the volume of the reservoir vs. volume of flow, and surface area of the tank relative to its volume. Having said that, you can get away with almost any reservoir if it's for intermittent use.

Good Luck!
 
Hard to tell from the photo, but make sure that your filter housing/assembly is up to the pump capacity, and also that the pump is not running faster than intended (thus creating higher gpm). I think most pumps are rated at either 1.8k or 3k.

Reduce flow restriction and reduce heat.

E.g., I run a 13.6@3k gear pump on a log splitter, and with the recommended filter head w/3/4 pipe fittings(rated to 20gpm), the oil got too hot. Upsized filter head(inlet/outlet are 1.25?), and the fluid temperature dropped dramatically.

Too many pipe adapters may affect flow, and from what I understand, high pressure hose restricts flow more so than the equivalent length of high pressure pipe.

Also, fluid capacity should be, I think, 1 to 1.5x pump gpm.
(Not a hydraulics expert by any stretch of the imagination).
 
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