an old silent b&w film (at least 70 years) of an unusual locomotive built by Baldwin's and used on the Pennsylvania Rail Road from 1940. They were unusual in respect of the cylinder and wheel arrangement. They were called Duplex Locomotives, they were massive, weighing in at over 300 tons and 140 foot long. Usually, for a locomotive of this size they are articulated machines but this one used a different method by dividing the driving wheels into two pairs and having the pistons rigidly centrally mounted and by having a power stroke at each end of the piston travel it could power both sets of wheels ... fine in theory. It also tried to combat what was termed as Hammer Blow which (briefly) relates to the dynamic forces upon the track delivered through the wheels as a result of the forces generated by the reciprocating mass of the machinery which had flywheels cranks and counter-weights weighing in their tons moving at very high speed, these forces easily damaged the track leading to accidents and bad riding which in some instances would cause the driving wheels to jump-off the track. The Duplex was an attempt to lessen this phenomena (amongst other ideals) but it was found that they suffered from violent wheel-slip at high speed which caused all sorts of problems. Experiments were made with steam valve settings and the like but were never fully solved. They were moved on to freight work but their sheer size and large wheels particularly (about 7ft diameter) were a hindrance rather than a help and with the advent of dieselisation taking place these monster sized machines were consigned to the scrap heap after just two years in some cases.
the wheel-slip phenomena is caught here at 1.20+
as an indication of the size look at the engineer (driver) sitting high up in his cab at the beginning of the film, the film quality is well-worn but worth perserveeing with if you like stuff like this.
Tags: Duplex locomotives, wheel slip, steam engines, Pennsylvania Rail road, ,
Location: Pennsylvania, United States (load item map)
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