450C Backhoe hydraulics

[PlugNickel]

Hello,
I have recently got a wild hair to put an old JD 93A hoe on my 450C dozer.
After finding and installing a rear mounting bracket and modifying the rear post mounts on the ROP, I started to look at the hydraulic hookup requirements...
I was surprised to see that Deere used a diverter valve for their setup and can't quite figure out why they would do this since I have an old AC HD3 with live hydraulics to the hoe and it doesn't need a diverter.

Since the hoe valve block (a 93A) is an open return, and the pressure rating is pretty much the same as the rest of the tractor, is there any reason why I couldn't just loop the main hydraulic line (before it goes into the dozer blade valve block) to the back and quick couple it to another line to the inlet of the dozer hydraulics?

It seems that this should work and power the hoe when connected, and when the hoe is off, I could just couple the lines together...
Not knowing why JD used a diverter valve, I'm thinking that with hooking it up this way, at least I could still use the blade hydraulics with the hoe on without messing with diverter valves...
Any thoughts?

Thanks,
Mark

[Willyr]

I would just leave the hydraulics live all the time and not bother to disconnect. But hey that is just me.

[PlugNickel]

Thanks Willyr,

That's my thought as well...'don't know why they use a diverter valve...
Any thoughts on just breaking into the main line from the pump and looping it to the rear to feed the hoe?
Can you think of any problems that this might cause?

Just trying to bounce this off of folks before cutting that 5/8" steel line...

[Willyr]

You should be fine. I dont know hydraulics well. I ran them on my New Holland 4630 with a 6 foot hydraulic broom (since sold it). The hydraulics on its front arms there were no diverters, just T's to branch power to 2 cylinders. I know enough to get me in trouble, so if some one else here has better info please by all means chime in, hate getting it wrong.

As long as you are only running just one item at a time I feel reasonable that you will be fine. You should not need to worry about diverters or priority valving.

[KenP]

deleted

[PlugNickel]

Yes, the 93A is open center (it came off of a 450C that was scrapped) and I expect that it will be about half the speed with the pump that is one the machine though without trying it, I can't say if it will be too slow or not.

I think I just ran into a problem though....
Just looked at the hoe valve block and it looks like there isn't a relief valve on the hoe it self and connecting it the way I was going to would put the 450C's pressure relief down stream of the hoe.
Looks like when fluid is directed to the hoe it won't have a relief.

Darn...gonna have to scratch my head further it seems.

I guess I could tie it in between the blade valve block and the axillary valve block...that would seem to solve the relief valve issue, but might restrict the flow.

I was talking to a JD mechanic the other day about that diverter valve that they use. He commented that he's seen pumps blown because someone pulled the diverter valve with engine running and the hoses not connected together. Don't know...

[JWB Contracting]

We did the same project about 5 years ago, except we used the twin swing cylinder 9550 hoe.

Instead of installing the diverter valve we opted to tie into the high pressure oil line feeding the dozer hydraulic valve. This was a considerable amount of work and planning as we needed to mount a relief valve under the seat and it does require a return line to the tank. We also installed a larger hydraulic pump off of a loader machine.

We opted out of the diverter set up as it is a pain to keep flipping between the dozer and loader functions. We reach back from the backhoe seat and pick up the dozer and then use the hoe to push the machine forward and then put the dozer back down for stability.

Very happy with the set up as we were able to adjust the relief value up to get some excellent digging power. Only think i would change would be larger plumbing to get the full benefit of the larger hydraulic pump. Comparing to the 450C loader backhoe that has the factory power beyond value (this is our yard machine).

Another way of going is to istall a loader valve with the power beyond valving in place of the dozer hydraulic valve. I may go this with if do it next time. Only down fall is having to use the separate lever for angling the dozer instead of the factory t-bar. Although now we added a 450G dozer with a hoe so not likely we will build another 450C machine.

The mechanic was correct on needing to conect the hydraulic lines run to the backhoe. Be carefull not to blow up you pump. You will know instantly if their is a problem when you start the machine as the engine will labour and you will most likely hear the hydraulic system whinning. Also important to use good quick couplers to risk the chance of them coming apart while operating the machine.

[PlugNickel]

Hello Jason,
That’s pretty much what’s been rattling around in my head concerning the relief valve under the seat; I was just on Ebay looking at them.
Yes, having to switch between the hoe and blade constantly when all you want to do is reach back to pick up the blade or perhaps lift the front of the tractor a bit seems like a pain.
So, did you just route the high pressure line from under the seat to the hoe and then from the outlet of the hoe back to the “T” handle valve block?
You mentioned that you had to route your pressure relief valve relief back to tank, so I assume you placed it on the “pump line” to the hoe.
What do you think about jus putting it across the two lines so that if the pump pressure gets too high, it just bypasses it around the hoe and into the “T” handle valve block as it would normally go anyway?
I don’t know, but it seems this would work as well and wouldn’t require another line back to tank.
Did you ever try using the dozer pump with the hoe?
If so, how slow as it?

Mark

[KenP]

deleted

[PlugNickel]

Thanks Ken,
Yes, I’ll get a service manual and a parts book for it, though to this end all I think I need to know is whether it’s normally open or closed to return, max hydraulic pressure, as well as it don’t have its own relief valve.
The scrap tractor I got the rear mount off of does have all the plumbing (diverter valve and so forth) as well as a high flow pump and before it’s all said and done, who knows?
I do appreciate your input, and might do as you suggest and retrofit this machine to JD spec’s in the end; that’s why I’m asking the question, to get different folks opinions and points of view.
In the mean while though, I’d rather ruminate upon a system that doesn’t need a durn diverter valve.

[JWB Contracting]

Hydraulic flow on installing a relief valve instead of a diverter.

We put a tee on the high pressure going into the dozer hydraulic valve and also the return coming off of the return line from the valve plus the bypass for the pressure relief valve.

We mounted the relif valve under the seat and used a piece of 2" flat bar accross the seat. It took some time to get the hoses right. We did not use a pressure guage to set the relief, just started out in the full relief position and kept turning it up until we could pick the back end of the crawler off the ground with the main boom.

We are very happy with the set up.

We have two 350C widepads loaders with backhoes that we have had in service for 30+ years and have had the 450C widepad dozer with the above set up for 5. Would not change a thing.

Good to take some caution and do some planning like the other posts mention. I have run a 350C dozer with the diverter valve. It was a real pain in the arse and sold it when we rigged the 450C up.

Open centre valve - take both hoses off and try and blow thru the high pressure input side of the valve. If you can it is an open centre valve.

I am not a hydraulic expert but i am fairly good on the the overall operation of the crawlers. We have pictures of me at 5 years old running the backhoe on the 350C widepads digging drainage ditches on the farm. I guess at a distance it did not look like there was an operator on the seat and even at that age i could lift the loader up and push the cat forward to keep digging.

Pick a plan and go with it. If you can get a diverter and plumbing cheap go with it, otherwise all it costs you is some fittings, a relief valve and hoses.

[digitup2]

The thing most dont think about a small pump is they have to be maxed out to work the hoe and after several hours of hard beating they will go out with a bang!!the bigger pump has a larger drive system as well so it isn't just the pump you replace,As for the flow divider it is there for a reason as the extra oil is not needed for a loader and sure as heck not needed for a blade they get jumpy enough going to the big pump .You will notice a lot more speed in the blade if you do big pump and way too much speed if the diverter isn't there Deere didn't put any thing on that wasn't needed in the hydraulic department.If you can find one use it . Digitup.

[JD430C]

My 450C came with a 24gpm pump from the factory and its never had a problem running the 6 way. It only has the 6way. I have run 450Cs with both pumps and wouldnt want to run one with the small pump.

I believe the 450C loader/backhoe crawlers used a 28gpm pump. I parted out one a few years age with one and it was factory.

PlugNickel- I have a diverter valve off a 450B, if interested let me know.

Andrew

[JWB Contracting]

I thought that the reason they went to a diverter valve is that the dozer hydrualic valve does not have the built in port for the power beyond valve like the loader valve bank or is too restrictive of flow to get the backhoe to operate properly.

We always put the bigger pump on dozer cats (350C and 450C) when mounting a hoe. I do not remember putting a heavier pump drive in though. We have had very little problems with the bigger hydraulic pump. Did not notice any issues with the blade moving to quickly, but i don't run the cats at maximum rpms as we do not remove the hoes to do dirt work or light clearing.

[digitup2]

I have done this up grade in several 550 series and it smartens the blade up considerable you definitely get a faster response on the blade with the big pump and in the early 550s you changed the internal drive shaft as well.You don't need to on a 350 or 450 pump mount is different.All my new 550s came with hoe mounts as my first 550 had a backhoe I just ordered hoe mount from the factory. The last two got winches on them so the hoe was never used we had several backhoes and an excavator at that point.I also feel it is hard on a dozer to work with the hoe in place.Digitup.