Variety is the spice of life apparently, so now for something different: a vintage crawler. The Cletrac was a crawler produced by the Cleveland Tractor Co of Ohio, USA. This old photograph shows a Cletrac, possibly a Model W, owned by Bill Groves in the 20s and 30s, and used on various contract work that he undertook in Australia.
The Cletrac 12-20 Model W was built between 1919 and 1932, and had a four cylinder engine with magneto ignition. Examples upto around 1930 had a Weidely OHV engine, with those afterwards having Cletrac's own power unit. Approximately 17,215 examples of the Model W were built in all, until being replaced in 1932. The tracks were supported by three rollers along the lower run of the track, with a single roller doing the job on the upper run
(not shown fitted in this photograph). The PTO sticks out the front of the crawler, beneath the radiator.
If you're interested in classic crawlers, the following video of various working examples spotted in Hastings might be of interest.