Power Beyond

[johnflimston]

Trying to run a JD Baker wrapper on a JD 4255. Hydraulics over pressurising. Would a free flowing return (rather than double acting spool) help and if so where do I fit one on the 4255.

 

[davidroberts30]

If its anything like a 3650 then you need to return it to the filter bowl

I might be completely wrong with yours tho

 

[Pheasant Surprise]

Trying to run a JD Baker wrapper on a JD 4255. Hydraulics over pressurising. Would a free flowing return (rather than double acting spool) help and if so where do I fit one on the 4255.

If your running from the PowerBeyond port on anything you should always be returning to a free-flow return. The amount of oil coming from a PowerBeyond connector is potentially up to full flow of the pump, therefore will overwhelm the (smaller) return oil capacity through a spool.

 

[Sharpy]

Assuming that its the same hydraulic set-up as the smaller 50 series (closed centre ), ideally you would have a closed centre spool block on the baler.

 

[kill]

I very much doubt power beyond could be fitted to a tractor of this age.
A 3/4 return may well help reduce pressure via restrictions.
I ran a JD 678 baler wrapper for several seasons and there's a simple lever to turn to alter between open and closed centre hydraulic systems

 

[Cmoran]

Had the same trouble with a Mchale wrapper years ago we fitted a second return pipe to chest valve of wrapper and put fitting on filter housing for it never a problem after that

 

[Hesston4860s]

If its anything like a 3650 then you need to return it to the filter bowl

I might be completely wrong with yours tho

Although you are right in what you say about plumbing to the filter bowl, and that’s how JD say to do it. It’s not actually a true free flow return to there, you will get a back pressure of about 150 psi at the port on the bowl. Only way I know of to get a true free flow return is to plumb upto the bung just above the handbrake adjuster !.

 

[johnflimston]

Although you are right in what you say about plumbing to the filter bowl, and that’s how JD say to do it. It’s not actually a true free flow return to there, you will get a back pressure of about 150 psi at the port on the bowl. Only way I know of to get a true free flow return is to plumb upto the bung just above the handbrake adjuster !.

I dont think there is a bung like the ones on the 50 series on the 4255

 

[davidroberts30]

Although you are right in what you say about plumbing to the filter bowl, and that’s how JD say to do it. It’s not actually a true free flow return to there, you will get a back pressure of about 150 psi at the port on the bowl. Only way I know of to get a true free flow return is to plumb upto the bung just above the handbrake adjuster !.

You had to do it that way to stop the pump starving itself of oil

 

[Cowabunga]

Those old 55 series surely don't have closed centre load sensing pumps that can have or require 'power beyond'. Basically, while they are closed centre, they don't have a sensing line to control a swash-plate piston pump.
What they do have is a radial piston pump where the pressure of oil pushes the pistons away from the central cam as pressure rises. They are not the most suitable units for constant oil flow through open centre spool valves and should, in fact, be used with closed centre valves on the bale wrapper or other implement remote valves. Many older round bale wrappers, like my McHale 991B, had convertible spool valves that require a change of plug in the valve body if my memory serves me well.

Its not that these tractors needed a free flow return as such, but that they have a service pump in the gearbox that feeds the engine mounted radial piston pump and that the feed pump can't keep up with the front pump's flow for long unless the return is plumbed directly to the filter bowl. Bareing in mind that my experience is with smaller tractors in the series and that the large ones just might have a different system in some way. Yes, there will be some back-pressure from plumbing the return that way, which may not be suitable for some applications. A free-flow return, otoh, may result in severe vibration of the plumbing due, presumably, to oil cavitation as explained in posts by others above.

 

[johnflimston]

All sorted now thanks. The old girl got me out of trouble on Saturday but I've had the PTO shaft on the 6820 welded up and we're now back on power beyond.

 

[YELROM]

All sorted now thanks. The old girl got me out of trouble on Saturday but I've had the PTO shaft on the 6820 welded up and we're now back on power beyond.

What have you welded up on a PTO shaft

 

[johnflimston]

Drive splines worn on stub shaft. Welded shaft to inner shaft.

 

[Cowabunga]

Drive splines worn on stub shaft. Welded shaft to inner shaft.

That sounds like a dodgy bodge. It may not be, but it does sound like it.

 

[johnflimston]

Advice on here is that it will work, only danger is buggering the seal.
Seal looks ok but I’ve ordered a spare in case. £50 for welding and £35 for seal versus approx £1000 for new parts.
Baled all afternoon yesterday with no problems so fingers crossed.

 

[Cowabunga]

Advice on here is that it will work, only danger is buggering the seal.
Seal looks ok but I’ve ordered a spare in case. £50 for welding and £35 for seal versus approx £1000 for new parts.
Baled all afternoon yesterday with no problems so fingers crossed.

There's certainly no room to argue with the figures.