I just recently bought an HO scale doodlebug and have a question regarding the prototype
I have seen pictures of them pulling cars, both freight & passenger..my question is..what was their pulling cababilities as far as number of cars..1 passenger? 3-4 40 foot box cars?
The term "doodlebug" refers to a very large variey of motorized of equipment usllally intended to operate passenger service on lines where the volumn did not warrent a rergular train. Doodlebug ranged from modified autos, trucks or buses to purpose built equipnent by companies like EMC, Pullman, McKeen (Mainly foe Spithern Pacific) and many smaller builders. The Budd RDC can also be considered a doodlebug.
In general doodlebugs were very underpowered and not capable of pulling trailers except in very limited circumstances.
I did some reasearch in three book about doodlebugs by Edmund Keity, Inteurbans Without Wires, The Shortline Doodlebug, and Doodlebug Country.
I assume you have the Bachman doodlebug. It appears to be freelance, although it does resemble some EMC or Pullman products of the late 20's- early 30's , as well as some from smaller builders. It is close in appearance to CM&SP (Milwaukee Road) second #5940 which was built by Pullman in 1930, but details ore different.
Based on photos in Keity's books, I would say generally no more than one passenger trailer (car) would be pulled. In most of the photos there are no trailers (passenger cars) although several photos have two.
There is a photo of a a Ewbank Electrical Transmission Railcar with a 905-ton train of 12 heavyweight coaches on the SP&S along the north bank of the Columbia River. It was a impressive test train, but there were no sales and the company went out of business.
Doodlebugs pulling freight cars would be extremly rare. The only photos I found were some 1920's home builts hauling single home built freight trailers, not standard freight cars.
EDIT
I see you also posted this question on the Model Raileroader board. Several posters there have given examples of doodlebugs hauling freight cars. I bow to their superior knowledge. However, I stand by my statement that it was rare.
I tried to sell my two cents worth, but no one would give me a plug nickel for it.
I don't have a leg to stand on.
Santa Fe had considerable success replacing early distillate and gasoline engines with diesel engines. M122 had enough power that it held down the yard switcher job in Paris, TX in the mid 50's.