Power Trac wannabe

[voodoo]

Hi Guys, been a while since I posted.

I recently bought this compact high tip skip dumper (first pic). I'm not sure if you have an equivalent in US. Their primary use here is for narrow access construction work and for load transfer to transport skips (second pic). The skip can lift 1 metric tonne.

It has permanent hydrostatic drive to all 4 wheels, using Poclain Posi-trac motors, accompanied with articulating centre pivot, no drive slip.

Anyway, I've been taken by the PT form factor for quite some time and considered that this could be modified in a similar way. I currently have a set of 3 point fork attachments that I built several years ago (pic 4) and am considering how they could be attached to work best.

There are two conflicting issues, convenience vs lifting ability, making this more of a problem than first thought.

If I retain the skip in position and somehow fit the forks to the skip, I would be able to attain a quick connection arrangement which would greatly add to the convenience. However, using the skip, sets the forks well forward of the pivot point which would greatly reduce the lifting ability. Additionally the skip would have to pivot to give rotation on the forks, which would then mean forward vision is greatly impeded.

The second option is to make the skip quick release, which would require some form of stand for the skip and an easy connection for the forks. Convenience reduced, lifting capacity increased and improved visibility.

The third pic shows how the front pivot point is arranged below the skip.

I,ve drawn up the pivot arrangement in Sketchup to show my current thinking which gives full rotation of the tipping ram, but I'd be grateful for any suggestions on how this might be done better. Additionally it would be nice to connect other 3-pt implements, although not an essential requirement.

I'm at a bit of a loss at the moment to come up with any other bright ideas. Obtaining the greatest lifting ability is probably the No 1 factor, but with convenience of quick change a very close second.

Any help greatly appreciated.

 

[alchemysa]

I'm no engineer but it looks to me like the skip is positioned so far back that when empty it wouldn't trouble that ram at all. In other words I'm saying that removing the skip might not provide significantly greater lift capacity anyway. However it also appears to me that your biggest problem would be visibility, and you may be forced to remove the skip for that reason alone. I've got forks and I can tell you that you do need a good view.

 

[alchemysa]

Heres another (possibly stupid) suggestion. Could you flip those curved arms over so they curve downwards like normal loader arms. That might make engineering for the forks, and possibly a bucket, a lot easier. Of course it depends how much you need that skip, but with a bucket up front you might never need the skip again.

 

[voodoo]

Thanks for the suggestions, this is just the sort of feedback I'm wanting to get me thinking outside the box and hopefully come up with a solution.

The weight of the skip should not greatly affect the lifting capacity of the rams. They are certainly capable of lifting the load. However, f I retain use of the skip, the forks need to be positioned forward so that the back upright of the fork is aligned with the front edge of the skip, (or the upper edge if fixing with skip vertical). Setting them up to each other, the visibility is actually better with the skip in dump position, as you can see below the skip leading edge to the forks.
However, with forks on skip arrangement, this sets the forks some 400mm forward of the pivot point, greatly reducing lifting capacity.

Flipping the arms is not an option for two reasons,
1) I want to retain use of the skip first and foremost,
2) There is a 6mm steel front plate which retains the front of the chassis rails. Without it, I think the strength of the chassis would be greatly compromised.

Keep the ideas coming!!

 

[Craig Clayton]

To Voodoo
I wish that I could get that model in Canada. I built a homemade power king type tractor some years ago and my bucket linkage was similiar to your lift arms. I would not change the lift position, as I like how it goes up against the dump bin. I would make a skid steer type of quick attach plate and make every possible attachment fit.
Craig Clayton

 

[voodoo]

Thanks Craig,

That's something along my thoughts at the moment, some form of drop arms like a skidsteer and a quick attach plate.

Just seems a bit of a pain to set up. I cannot see any way for a quick turn around changing between skip and attachments.

 

[voodoo]

I think I might have the problem cracked.

I've accepted that the skip is going to have to come off to make this work properly.

By making "proper" lower loader arms I can make this into a loader frame. The arms can be attached by sliding into the bracket and then pin fixing in position. With this arrangement there is no modification of the original construction, so all can be left back as is.

The addition of a set of arm stays would allow these to be stored in an upright position so that I could just drive into them and pin on.

The use of a quick attach skid steer bracket is also possible. (yet to be drawn).
The existing frame for the forks is going to have to go, just shown at present for positioning.

What do you guys think?

 

[voodoo]

Any of you guys know where I can source a quick hitch frame for the loader arms here in the UK? All the websites listing any seem to be in the USA.

 

[MossRoad]

Being a Power Trac owner, I can tell you that your lift capacity will be greatly reduced by putting those forks out that far in front. Be prepared to tip the unit on its nose, as we do with our Power Tracs on a regular basis. Also, be aware that your center of gravity will move forward as you turn the unit to either side because the unit gets shorter. Many Power Trac owners call this the PT Pucker. Just the nature of an articulated vehicle.

 

[voodoo]

Thanks MossRoad,

It's a problem I'm only too aware off. The current mounting frame for the forks will have to go and a lighter frame made to move them back in to the pivot point. I've only shown it here for arrangement positioning.

The arms are shown with a forward angle mainly to look correct, but I might have to consider dropping them vertically to stay as close to the front headstock fixing as possible.

As an experiment, with the skip tipped forward I slung the forks to the front lip and chained then back over the back edge to hold in position. This set the upright of the forks about 18" forward of the skip pivot point. With only the weight of the forks, skip and myself @ 220lbs I was able to "bounce" the machine. Wheels never left the ground or anything, and I think it was more the flex of the skip and the tyres, but it gave an early indication of the limitation of the arrangement. To lift anything like a useful load, the back of the forks is going to have to be vertically down from the skip pivot point.

It should be possible to add a weight frame to the rear chassis, but I'm reluctant to put any more than reasonable stress on the pivot.

More thought required I think !!