still in use commercially....

[Richard Coutts-Smith]

I assume this one was the High Speed Tractor version?
http://www.youtube.com/watch?v=zsXzCD0XzU0
Rich.

[maple_leaf_eh]

The term is Spar Yarder. The idea is to drive the chassis as high up the hill as possible. Set the anchor cables and deadfulls. Then rotate and raise the mast. Run a very long overhead cable to somewhere near the bottom and tension it almost straight. There is a cab for the operator who winches logs up the hill to a landing where an loader puts the logs on trucks. The dangerous job is down on the hillside where men in helmets and spikey boots set choker cables and dodge runaways. The Madill company in Nanaimo, BC that did hundreds of conversions. If you search the heavy equipment auctions there are almost always a few on offer.

A second company that use Sherman chassis' for rough terrain use is Finning. Put a big air compresser on one end and a very powerful rock drill hanging off the nose. The companies use these to drill deep holes for blasting hard rock on construction projects.

[tankbarrell]

That yarder is not on a Grizzly chassis, or if it is, all of the features identifying it as such have been changed.

[things_green]

as I stated Adrian, I'm no armor expert......So if its not based on a Grizzley....just a fan of things green....
so what was it?

the original image I snapped while passing on a train....so I went back (what else would one be doing on Christmas Eve?).....and took some better shots.

[tankbarrell]

Brent, almost impossible to say without a close look but the transmission is the late single piece which was not used on Grizzly. The tracks are T47 rubber chevron and these are features generally seen on 'standard' US production vehicles. It could be Sherman based or M7 Priest.

Of course, all those parts are interchangeable as assemblies so it could have started as a Grizzly and the steel CDP track and sprockets could have been changed to rubber for road use but it seems unlikely that the complete transmission assembly would also have been changed.

It could be Sexton based but it has Sherman bogies whereas most Sextons had specific bogies but again they could have been changed.

Because of that, it would need a close examination to determine its origins and that assumes enough original material is left to allow that!

[Luke R]

Just a thought, Could there be a bit of confusion between Madill a Canadian based company that built spar yarders on sherman/HST chassis's and the Grizzly the Canadian built shermans.

Luke

[maple_leaf_eh]

Originally Posted by Luke R

Just a thought, Could there be a bit of confusion between Madill a Canadian based company that built spar yarders on sherman/HST chassis's and the Grizzly the Canadian built shermans.

Luke

Any similarity would be coincidental. From what I've read, the most common donor chassis was the M32 ARV followed by the HVSS postwar Sherman. So much so, the model number is repeated in their conversion model number. I haven't seen anything that suggests country of origin, but there would have been enough surplus vehicles in the fifties and sixties to meet demand. And, from what I can tell, these arrived already demilitarized (saves the freight).

As has been implied, the modular design of the M4 is the key to the success of the Madill spar yarders. The three-sided chassis is tied together on the front with a final drive, with three (or four!) suspension stations per side, and whatever engine the company liked. As far as I can tell, the logging companies didn't want anything old or esoteric. They needed dependable, fixable and cheap fittings. Whether it is the engine to move the yarder around, or the winch drives, these were not nostalgic items. These are hard working tools! Used until the contract or season was done, fixed enough to make the month end, and if the company has to slim down, whatever will sell fast at auction goes out of the yard. Gradually, the heavy duty excavators seem to have taken over as the platform for spar yarders.