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Old 01-11-2016, 12:23 AM
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DADSGARAGE DADSGARAGE is offline
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Default Re: PC1800 Front Shovel (1/12)

The best thing for me to do is share the results of all the different tests so you all know what is happening.....

The pump "should" be moving 3000cc/min or 50cc/sec. The total combined volume of the two boom cylinders is 241cc, so at 50cc/ sec it should take 4.82 seconds to fully extend both cylinders. Keep in mind this does not account for any slip in the pump and would be with no load or restrictions.

20lbs was used for the load in all the tests

First test

1/4" ID suction line tank to pump, the blue1/4" OD tubing from pump to valve body, the ID of the tubing is .180", the same 1/4" OD tubing was used on the return from pump to tank. PRV set at about 275 psi on a 0-600 psi gauge. System pressure with no load and the controls in neutral was about 60 psi. It took 7.5 seconds to fully extend both cylinders and pressure was about 220 psi.....funny not what I was hoping for...lol

Second test

Changed the suction from the tank to pump up to 3/8" ID and changed the return line from valve to tank up to 3/8" ID as well. Pressure in the neutral position was now zero, and operating pressure dropped to about 200 psi. The time to extend the cylinders increased to just over 9 seconds. So I was getting some restriction in the return using the smaller tubing...interesting.

Third test

Increased the feed line from the pump to valve body to 3/8" ID tubing....no changes

Forth test

Check the flow rate of the 5/32" OD tubing (.106" ID)....removed the 3/8" return line and installed one 5/32" OD tubing. With the controls in neutral I turned the pump on for 30 seconds (220psi) and got almost 1500cc which is 3000cc/min, again not what I was hoping for...lol....really thought the small tubing was restricting the flow to the cylinders but that is not what is happening.

Test 5

Increased pump speed 600 rpm to 2000....again very little change....scratching a hole in my head with this one...lol

Last test

Dropped the pump RPM back down to 1400, increased suction to 1/2" ID used the same 3/8" line pump to valve but reinstalled the blue 1/4" OD tubing on the return....the result where nearly the same as the first test. Which makes me think that some of the flow in this open center valve is still bypassing the spools even with them fully open to the cylinders. The pump is supplying the proper amount of flow but if all of that flow isn't getting to the cylinders where is it going?? (and no there isn't a leak some where...lol)
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