Im not sure if you have a copy of the Petter Oil Engines catalogue re-print produced by David Edgington? If not, I am sure the photographs below will be of interest. The catalogue shows two old photographs of what I believe to be Fowler Cement Mixers powered by a 5hp Petter M (see below).
10 cu ft capacity drum cement mixer powered by a 5hp Petter M (Appletop I suspect from the the photographs in this months Stationary Engine Magazine) featuring a power loader and automatic water tank:

10 cu ft capacity drum cement mixer powered by a 5hp Petter M (Appletop I suspect from the the photographs in this months Stationary Engine Magazine) featuring a power loader, automatic water tank and hoist winch which could be operated simultaneously with the mixer:

Regards,