My New Performance Super Major Story.

[Ian H]

Nah, he was just having a laugh. Had a little bit of a chat. He was surprised at how old it was, but if it works and does the job...

Anyway, latest development is I got the backhoe on. It's an old McConnel PA44 dating from the early '70's I believe. I got it all hooked up and the hydraulics connected up to the tractor and had a little play. It is not as slow as I expected. This may be down to the tractor being a NP model, which I believe has a higher capacity hydraulic pump compared to previous models. The slew in particular was rather quick, despite narrow pipes being specified as OE to restrict the flow. Even on fairly low revs the relief valve on the tractor would open on the slew.

1,200rpm seemed adequate for a decent digging speed, but of course out of curiosity I thought I would try it at max rpm to see how fast it could really go. Well it felt like a kind of initiation ceremony - got anointed in oil. That's right, I burst my first hose... Still better now under test rather than when working for real. Many of the hoses are old and could do with replacing, I do have equally old spares, so the policy is to take spares and replace them as and when they blow.

As It happened this particular hose I did not have a spare for, but a replacement was ordered and quickly arrived so all is well. Anyway, at least it will dig as fast as ever I want it to. I think the power arm deserves it's own thread!

[Old Hywel]

I’ve recently replaced almost every hose on a mid-seventies International Wainroy digger. Cost: roughly £1000. While it may seem bonkers spending so much on a machine that age, I’m now fairly confident that I won’t finish each day smelling of £50 worth of oil.

[Billy26F5]

Burst hoses are always irritating, but often it does work out better to replace doubtful hoses sooner rarther than later. I think all Super Major's have the same hydraulic pump, which is different from earlier pumps. What is different is the gear ratio, as the NP PTO is slower the PTO to pump gear ratio is such to try and match the previous overall ratio for the pump. NP tractors also all have the later relief valve, enabling sustained 2500 psi, this valve appeared shortly before the NP was introduced and often mistakenly said to be a feature of the NP only. Would love to see this backhoe.
Sandy

[Ian H]

Here is the McConnel PA44 mounted on the tractor:



As you can see it can be fully offset to dig parallel to walls, as well as increasing the reach.

I kind of made it into a backhoe loader:

[Billy26F5]

Looks good like that, hope you can easily swap between that and normal as you need. Neither are very heavy implements but they will add up to considerable extra weight. Be careful not to overload the loader as there's nothing holding it onto the back.
Sandy

[Old Hywel]

When ditching with the Power Arm, it’s common to use the boom to repeatedly push the outfit forward into a new position as work progresses. Occasionally, if the tractor doesn’t move easily, the forces involved can cause the linkage (and the whole machine) to move upwards.
This isn’t a problem with open tractors, but after the introduction of safety cabs several operators were killed or maimed after being crushed against the cab. I believe some kind of lock mechanism was developed to counter this dangerous situation.
Something to be aware of for operators.

[Hair Bear]

It's a method all jcb drivers use. With the double acting system on the loader and a rigid frame as well you can toboggan along on the front bucket and not have to keep lifting the stabilisers.
As you say Sandy, a push with a 3pt backactor will ride the link arms to the top before moving the machine.
1980 public information film here... https://www.youtube.com/watch?v=Qbj8CYjIupQ

[Ian H]

This can't happen to a properly installed PA44. In fact it can't really happen to a badly installed one as you don't sit on the machine. Whilst it does use the two lower links, the upper link is not used and is replaced by a rigid bracket that the machine locks on to. It is this that takes most of the load, the two lower links are disconnected from the lift links and are just used as struts. I have of course made absolutely sure that the bracket is very solidly connected to the tractor, with absolutely no play in it. The end result is a rigid attachment that has almost no hint of movement, no matter what you do with it, unless you command it to move!

[Billy26F5]

Very interesting system. I think the first JCB backhoe was actually PTO driven and was lifted by the tractor hydraulics. The subsequent JCB Mk1 couldn't have the same problem as it used a separate double acting ram to replace the tractor hydraulics which were not fitted (neither was the PTO). Very clear film.
Sandy

[Hair Bear]

The film was a bit of an odd one. I clearly remember it going out one Sunday lunchtime - the only time I ever saw it broadcast so must have sunk in well! I wonder how many incidents there had been to warrant making it?

[Ian H]

Yes this machine uses its own double acting ram for lifting and lowering. It is quite capable of lifting the tractors back wheels off the ground and taking all the weight on the jack legs which makes for a particularly sturdy digging platform, and is the recommended way according to the manual when digging. Due to the legs being at an angle, any slack in them is also taken up by the the weight on them meaning zero slop and it feels solid as a rock.

I had heard stories about being crushed by tractor mounted machines, but did not know how it happened. That video explains it. That does not mean there are not other ways of getting crushed. For example my machine has a 270 degree swing which is interesting...

[Billy26F5]

Very different from most, which have 180 degrees slewing. The tilted legs do indeed give a more solid stance, but they will suffer more wear as a result, so something else to keep in mind.
Sandy