The TR1, M26- M26A1 Knuckley a.k.a The Dragon Wagon.

IPaul72: Greetings All! Ever wondered how those broken down tanks and captured tanks were moved about during the war? Well here is an article they may answer just a little bit of that question...   The M26 Knuckley a.k.a The Dragon Wagon.     In the April of 1943 a heavy tractor trailer combination was submitted to the Aberdeen Proving Ground. This was a forward control tractor with an armored cab and was produced by the Knuckey Truck Company of San Francisco. You may well be forgiven if you have not heard of the Knuckey Truck Company, it was never a well-known name. Knuckey specialized in custom build heavy off road machines normally found in use with open-cast mines and quarrying applications.  Knuckey had apparently adapted the chassis of an existing vehicle, then fitted an armored cab before passing to the army for its evaluation. Apart from its massive size the most striking feature was the angular armored cab with its heavy shuttered windows and radiators, a platform was provided for the fitting of a M49 ring mount for anti aircraft defense weapon.  Power was provided by a huge Hall-Scott 400 six cylinder petrol engine. This was to be placed over the front axle it drove through a four speed fuller gear box and three speed transfer case to the rear bogie and a patented Knuckey center-pivoted walking beam rear bogie. The walking -beam configuration would provide 18 inches (457 mm) total movement. The rear wheels were driven by chains that were lubricated via a total loss oil system, small oil pipes dripping oil on to the chains that would end up on the road. Maximum road speed was 26 MPH or 42 KPH and a fuel consumption of 1.08 miles per gallon! Little attention was paid to comfort and the six man crew, although the driver was given hydraulic assistance on the steering. This could be considered very little compensation for having to sit inside an armored box next to one of the largest petrol engines in the world.  Braking was only on the rear wheels and they were operated by air assistance, there were also separate hand controls were mounted to the steering column for operating the breaks on other side wagon to help manoeuvre during recovery operations. Three winches were provided twin 60,000 lb at the rear with a single 35,000 lb fitted to the front. The rear winches operated from a platform at the rear just before the spare wheel, the front one was operated from inside the cab. The Knuckley wasn't short when it came to carrying recovery equipment, there was a folding 'A' frame that was carried and could enable the vehicle to act as a recovery unit. There was also the the ancillary equipment, this included oxygen and acetylene bottles for cutting and welding rigid straight bars for recovery. There was also a "whiffletree" for use with the recovery equipment and the usual complement of pioneer tools and vehicle maintenance/repair equipment.      A single spare wheel for the Tractor and trailer was fitted behind the cab on the right hand side. A small crane was provided for the handling of the spare wheel, also large semi- automatic fifth wheel coupling was fitted to the rear of the of the rear bogie setup.   After initial tests the A P G approved the design and the tractor was to be put into production. Sadly Knuckey lacked the production capability for the numbers that was demanded by the army. So the production contract was awarded to the Pacific Car and Foundry Company from Renton Seattle. This company was better known for producing railway locomotives the car in the name was a reference to the rail cars. The Tractor that the company produced was to be described by the company as the TR-1 and it was to retain most of the features of the prototype. However, the seven man armored cab was to become a little more cluttered, the original Hall-Scott Model 400 engine was replaced by a purpose built military model 440 Hall-Scott petrol engine. Knuckeys involvement in this project was now to provide the rear bogies for the tractor in June 1943 after the design was standardized.    The next change would come in the October of 1944, this was an open cabbed unarmored version that would standardized as the M26A1. This was due to the fact that the tactical advantages of the armoured were no longer needed. The total production numbers of the M26 between 1943 and 1945 was 1372 many of these would remain in Europe after the war and would continue to be used by Heavy Haulage operators many who would lose that big heavy cab.   Trailer specs of the M15 trailer.
The M15 trailer was designed for use with the M26 and M23A1 tractors.  It had Eight large 14.00-24 combat tyres taking the load at the rear of the trailer the suspension was solid walking beams with trunion shafts. Full service air brakes provided the braking power but there was no parking brake option on this system. The wheel base of this trailer could be increased or decreased for aid in loading or transporting. To the rear there was two large ramps that allowed loading of other vehicles in the field, raising of the ramps was done by the winch on the M26. Two strut legs would support the front of the trailer when it was not coupled to the M26. Stowage for the recovery equipment was provided on the upper deck toward the front of the trailer. Wire cable guides were built in to the trailer so the winch wires from the M26 could be threaded through these during recovery operations.  The M15 would have its payload increased from 40 Tons to 45 Tons and would be known as the M15A1 and would have hinged covers over the rear wheels it would again be modified to cope with the heaver tanks. This was then to be known as the M15A2 some of these would remain in service till the Vietnam war. The M26 Tractor and the M 15 Trailer make up the M25 Tank Transporter.    All Credits go to a Mister Joel of Parola Historical vehicle museum Finland.   Kind Regards IPaul72