Petter M type 5 horsepower - A chronology of development and modification - (confessions of an Anorak) Copyright - Roland Craven 2002
The support and encouragement of Philip Thornton-Evison is freely acknowledged as is the help of: Colin Purchase, Graham Tyler, Graham Howland, Dave Shortland, Eric Brain and John Ambler.
Like the previous document, on the Petter S type, this too is a hostage to fortune. It is based on evidence I have seen and on discussions with knowledgeable people. Inevitably there are gaps in both knowledge and the pictures. If you are able to fill a gap, and either complement or contradict any of my conclusions, then please contact me. Feedback is always appreciated whether it be praise or criticism or simply thanks.
None of the change points proposed are exact nor did they occur cleanly at a single instant. It appears that within Petters modifications and working practices often came and went several times before finally becoming the standard. Petters also seem to have sometimes fulfilled orders by using stocks of old parts especially after the move to Loughborough. Some of the more bizarre variants found in the smaller sizes do not seem to exist in 5hp form; unless you know different?
To those who assert that all Petters are the same I say simply; "read on".
Caution. Old Petter or OEM literature should be treated with healthy scepticism since it can contain "artistic licence" and or show out of date models or features.
Dating is availble through the website and list of preserved engines is available from the museum Archive menu.
The smaller sizes of engine are well covered by a booklet also available from Stationary Engine Magazine If you need transfers, a reprint manual, or the booklet see also Stationary Engine Books A downloadable manual (pdf) for the 1923 and 1931 models can be found at Internal Fire
The information and conclusions are presented in text and summary-table forms.