Allis Chalmers HD14

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AC HD14

This is an Allis Chalmers HD14. The photos were donated to me, so I cannot precisely date the machine. The configuration is classic of the late 1940's however. The engine is visibly a GMC 6-71--no doubt a 2 valve standard model--not the 6-71N that we are more familiar with. The blade is a bit of an afterthought it seems. Note the winch on the back of the tractor. The cable goes forward somewhere (usually down the side of the machine) and gets into the rigging to lift the blade.

As is typical of rear drive winches, the winch doesn't work when the clutch is released so neither does the blade. Some machines of this vintage I have seen had the cable passing directly over the top of the machine usually in a tube to the back of the machine but this one appears to come forward on the left side of the machine just above the fender.

Pull pans or scrapers were popular for dirt moving in this era, and the same lift cable could control the scraper. The blade would either be removed or tied up and the control line used for the scraper. Where are hydraulics when you need them? The next level of innovation was for the manufacturers to figure out that blades were pretty common features for track dozers so they put a 'hard nose' on them which allowed the rigging to be directly attached to the radiator guard. They followed this with a 'front drive' winch driven off the front of the engine. This made for a blade you could lift whenever the engine was running, unlike the rear drive that required the clutch to be engaged.

Not being very imaginative, when hydraulics became available in the early 1950's, they then stuck the hydraulic pump on the front of the engine sort of replacing the cable control unit that had by then migrated forward. These things took more power than the engine makers had envisioned coming off the front of the engine so pulley and connection failures weren't all that uncommon.

Finally the the 1970's, the hydraulic system migrated to the back of the machine with the pump driven off of an auxiliary drive on the torque converter. Thus we see the controls for the blade go a full circle -- From Cable on the back, to cable on the front, to hydraulic on the front to hydraulic on the back.

If there was any machine that doomed Allis Chalmers to ultimate failure in the market as compared to Caterpillar it was probably this machine and its contemporaries. The real problem was the engine. It isn't that the 2 stroke Detroit Diesel was a good engine, it just wasn't good for a dozer. The torque curve on the Detroit Diesel is very flat implying that the engine had little or no lugging ability. This contrasted to the Cats of the day that used a slow speed (around 900 RPM) 4 stroke high torque rise engine. The Cat would chug along and if the pushing got hard, it would lug down until you took pity on it and released the clutch. The Detroit Diesel engine would just quit if it became overloaded. To compensate for this the operators tended to run the Detroit engines at full throttle (because they wouldn't run anywhere else and produce any power), and also the manufacturers used a more powerful engine in an attempt to compensate for the lack of torque rise. The penalty was paid on the back end of the machine. They ripped out the final drives with abandon, and created a reputation for unreliability that haunted Allis Chalmers forever and left the market open for Caterpillar to dominate.

In the 1960's Allis Chalmers bought Buda and refit the Buda line of engines for their equipment, but it was too late. A whole generation of people had grown up with AC's that would rip, snort and tear themselves apart and Allis Chalmers is mostly history. The Fiat Allis lines in the 60's and 70's were as good as them come, but few came, and around 1980 Fiat Allis abandoned the large dozer market.

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