450C Hydraulics Not Working!

Alaska907 · Post by **Alaska907** » Fri Oct 16, 2015 11:29 am

Hey all,

Using a 450C crawler loader with the multipurpose bucket and while using it the hydraulics went out. The machine will move forward and backwards but the hydraulic controls aren't even trying to move.

The operator added fluid, thinking that might solve the issue but after trying to run it again, we noticed there was no pressure being generated in the hydraulic tank.

Is it safe to assume the pump has gone out?

Thanks in advance for your help!

NWJD fan · Post by **NWJD fan** » Fri Oct 16, 2015 7:37 pm

It is not uncommon for the splined coupling that connects the hydraulic pump to the pump drive on the engine to fail. If it worked 1 minute and not the next this is a likely candidate. If there was a slow noticeable decline in hydraulic performance it may be the pump.

Alaska907 · Post by **Alaska907** » Sat Oct 17, 2015 10:10 am

I checked and verified that the shaft was turning.

I pulled the relief valve out and didn't really know how to determine any failure with it. I know that the operator wasn't too sharp about keeping the hydraulic tank full, so I mildly suspected a smoked pump.

jsal · Post by **jsal** » Sat Oct 17, 2015 11:08 am

If the shaft on the engine is turning does not mean the pump shaft is turning take pump off and look at the coupling

JIM

Stan Disbrow · Post by **Stan Disbrow** » Sat Oct 17, 2015 2:14 pm

Hi,

The splines inside the coupler may be gone on the pump shaft end. So, you would see it turn, but it not be driving the pump. The couplers are made from a softer metal on purpose so they die and not damage the more expensive part.

If it just plain quit, this is what I would be looking for first.

Stan

Alaska907 · Post by **Alaska907** » Tue Oct 20, 2015 4:53 pm

Did not find anything broken with the coupler. Splines are fine. Should the coupler have a dowl pin through it to prevent the couple from sliding down the shaft, away from the pump?

LeonardL · Post by **LeonardL** » Tue Oct 20, 2015 5:09 pm

There should be a spring pin / roll pin that goes through the coupler to prevent it from sliding away from the pump. There are also snap rings on the drive shaft itself.

Alaska907 · Post by **Alaska907** » Wed Oct 21, 2015 1:26 am

LeonardL wrote:There should be a spring pin / roll pin that goes through the coupler to prevent it from sliding away from the pump. There are also snap rings on the drive shaft itself.

I found the snap rings on the drive shaft but it seems to allow the coupler enough space to slide away from the hydraulic pump. I'm thinking this coupler has just been held in place for a while and then recently broke free with no roll pin to hold it in place.

I'll see what I can do about getting it back together and figuring that is the fix.

Thanks!

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450C Hydraulics Not Working!

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