Back in time when the track type tractor was still considered a new tool for earthmoving, there were dozens of companies offering attachments to outfit these machines for work. Isaacson were one of them. By RICHARD CAMPBELL.
With the end of the great depression in the early 1930s, those tractor manufacturers who had survived the financial turmoil began to build new tractors and expand their businesses.
Without exception, none of these tractor manufacturers built their own attachments.
That task was left to a multitude of ancillary manufacturers, some of who lasted a few years and others which went on to become legendary.
There was also a certain degree of specialization among these smaller attachment builders.
Taking a look at some of the participants, at the top were LeTourneau, LaPlant-Choate and Bucyrus-Erie who built practically everything imaginable that could be fitted to, or towed behind a track type tractor.
LeTourneau’s equipment was all cable-controlled while both LaPlant-Choate and Bucyrus-Erie also built hydraulically powered equipment, LaPlant-Choate in particular being a pioneer in this field.
Then there were the second line of attachment builders including GarWood, Baker, Heil, Slusser-McLean, Be-Ge, Austin-Western, Kay-Brunner, Wooldridge, Ateco, Adams, and the subject of our story, Isaacson.
The third line were the really specialist builders such as Hyster and Carco who built mostly forestry oriented attachments and built them well.
The Isaacson Iron Works was established in Seattle Washington by ex-Swede John Isaacson in 1906.
Initially providing steam boilers and logging accessories such as chokers, grapples and other cast implements for the logging industry in the Pacific Northwest, Isaacson branched out into tractor attachments after continual advancements and mechanisation in the forest industry made some of its key money earners obsolete.
Its first product was a rudimentary bulldozer blade for cutting in logging trails and soon after that the first scraper, a hydraulically operated machine, was introduced.
During WWII Isaacson made propeller shafts and rudder posts for US Navy “Liberty Ships” and were recognised by the US Government for its high quality work.
During the 1940s, many of the attachment companies formed partnerships with the track type tractor manufacturers for preferential supply of their equipment.
And so it was that LeTourneau and LaPlant-Choate were most often seen on Caterpillar tractors, GarWood and Baker equipment on Allis-Chalmers tractors and Heil and Bucyrus-Erie equipment on International Harvester machines.
Isaacson had an affiliation with Cletrac, and to a lesser extent, International-Harvester, although its blades could be found on any brand of tractor if the user had a preference for them.
Most of the attachment companies had their own trademark names for equipment and Isaacson was no exception.
Its bulldozer and angle dozer blades were known as “Klearing Dozers” while their towed scrapers were known as “Karry-Skrapers”.
Isaacson’s most popular products were its bulldozers, widely used in the forest industry where cable-operated bulldozer blades were preferred because of their high lift ability, enabling them to get better leverage on stumps and allowing them to stack logs at the skid without these hanging up under the blade.
It also manufactured a range of logging arches to cruise logs to the skid known as “Karry-Arches”. These were very similar to Carco and Hyster arches of the period and can be difficult to identify in photographs.
To its credit, Isaacson manufactured everything itsold ‘in-house’ and were not reliant on other manufacturers for hydraulic pumps or PCUs (power control units). Thus the company had total control over the quality of its finished products.
In the earthmoving sphere, Isaacson had a range of cable-controlled scrapers and matching PCUs plus towed rippers which were loosely based on LeTourneau’s designs of the period.
There was a difference however in that Isaacson offered hydraulically operated as well as cable operated rippers.
As the motor scraper had become very popular following the introduction of the LeTourneau Tournapull, Isaacson decided to have a go at creating one of its own.
As R&D costs were very high for such a project, Isaacson improvised by adapting an existing International-Harvester TD-18 tractor from tracks to wheels and attaching one of its KS700 Karry-Skrapers semi-permanently to the drawbar.
A double drum PCU was driven off the tractor’s front crankshaft pulley and the cables fed back to the scraper via tubing.
Isaacson called the resulting hybrid the “Wheel-Tor” and examples were tested in 1946.
Trials were not very successful due to manoeverability problems and the project was subsequently shelved, but the machine remains an interesting curiosity.
As mentioned previously, the tractor attachments’ market was very heavily populated in the 1940s & 1950s and a lot of companies fell on hard times when the tractor manufacturers began to build their own attachments.
Some, such as LeTourneau were large enough to stand on their own while others went down the merger path like International-Harvester & Bucyrus, and Allis-Chalmers and Baker, thus assuring their long term survival.
So it was that in 1955, Isaacson’s forestry and earthmoving equipment division were sold to the Pullman Standard company, manufacturers of railroad carriages & rolling stock.
It must be said that this was a very unusual marriage, given the two companies’ dissimilar backgrounds.
Pullman Standard did very little with the brand other than re-marketing the cable-control scrapers under the Allied Tractor Equipment brand name, and discontinued production of just about everything else.
Earthmoving & forestry it seems were not high on the company’s list of priorities.
What remained of Isaacson’s designs & patents were eventually sold by Pullman Standard in 1967 to the Young Corporation of Seattle, Washington, who remain the owners to this day.
Young have a very long history in the forest equipment industry and the acquisition of the Isaacson line merely bolstered its presence further.
Interestingly, you can still buy an Issacson Karry-Skraper – built strictly to order and wearing Young branding!
The New Zealand Connection.
Your author has seen very few Isaacson products in New Zealand and certainly no scrapers.
However there are examples of its arches, blades and PCUs to be found.
They are very, very rare in New Zealand (and Australia too), as it would appear that those examples that arrived here came already fitted to machines, most of them Cletrac & I-H.
There does not appear to have been any authorized distributor in the South Pacific for Isaacson products which would account for their scarcity.
For the Model Collector
Well goodness me, for such an obscure brand there are two models available, one in 1:50 and the other to 1:25 scale.
Both are manufactured by Spec Cast of the USA, and represent an International-Harvester TD-24 with an Isaacson front cable bulldozer frame with straight bulldozer blade, and towing an Isaacson Karry-Arch.
These are both good models with better than usual detail, metal tracks on the dozer and arch, and can still be obtained reasonably cheaply.
There is also another item for the serious collector – an add-on front PCU, blade and frame to fit the long out of production NZG Caterpillar Sixty.
This is exceptionally well made but extremely rare and does involve some surgery to fit. The end result is very impressive though.