Hubbard Steamcycle Restoration


The Hubbard Steamcycle as it appears in 2012

Steam Power Restoration  (originally posted on 5/3/06)
Restoration of the Hubbard Steam-Powered Motorcycle

This project involves restoration of a rather rare breed of machine. Very few steam-powered motorcycles are known with the majority of historic "steamcycles" residing in museums (e.g., the "Field" steam motorcycle).  There has been very little commercial exploitation of applying steam power to two-wheeled vehicles, so most "steamcycles" that come to light are one-of-a-kind prototypes built by hobbyists and steam enthusiasts.  The steamcycle restored here is no exception. It was custom built by Arthur "Bud" Hubbard of Monroe, CT during the early 1970's. 


The two photos at left were taken by CAMA member Kevin Shail. This is what the Hubbard Steamcycle looked liked after spending 10 years in a chicken coop.  Dick Greene, a founding member of CAMA, owned the steam motorcycle, having purchased it from Arthur "Bud" Hubbard, the bike's builder.  Dick put it in the coop with intentions of fixing it up, but never got the chance, having passed away unexpectedly in 2006.  

Jim Anderson, another CAMA member purchased the steam motorcycle from Greene's estate and set to disassembling the bike to clean it up and hopefully get it running.  Upon disassembly it was found that the bike had sustained significant damage from rust, and the boiler was perforated.  Every usable part was individually cleaned and polished over a 6 month restoration process. Of great help was the fact that Bud Hubbard had kept a thorough notebook of his building progress and technique, which made the restoration that much easier.  The steam motorcycle now resides in CAMA's Industrial Hall of Steam for all to see.

Mr. Hubbard built this steamcycle in the early 1970's.  He was however following a two-part article published in The Model Engineer and Electrician published in April of 1918!  This article is entitled A Design of a Steam Motor Cycle and was authored by Thomas Hindle.  The paper described in detail the construction of a steam motorcycle and included drawings and construction data. From a careful reading of the paper it is apparent that Hindle never actually built this motorcycle himself! It appears to be a paper exercise.  More than 50 years later, Bud Hubbard turned this design exercise in reality.   Therefore, all of the post-construction troubleshooting was left to Mr. Hubbard himself.  It is a testimony to the skills of Arthur "Bud" Hubbard that he 1) built this in the first place and 2) did extensive testing and improvements to his design to actually get it running on steam.  Mr. Hubbard kept a notebook that chronicled both the construction of the steamcycle and it's later testing and modifications.  His notes exemplify inventive spirit and clearly show the interative process involved in building anything mechanical. 

The following photos were taken during the restoration process. 


The motorcycle frame is a 1956 Maico of East German manufacture.  The powerplant was hand built over about 4 years starting in 1969. The cylindrical, triple-coiled, tubular steel flash boiler is just visible mounted down low below the engine.  

Powerplant left

A closeup of the handmade powerplant. This is the left side with most of the feedwater handling components.

right side

Right side of the powerplant with most of the fuel handling components.  The steam engine has successfully run on compressed air since the restoration.

steamcycle engine

A closeup of the 44 pound handmade powerplant. This is the left side with most of the feedwater handling components.

Steamcycle engine

Right side of the powerplant with most of the fuel handling components.  The cylindrical tank at the 6 o'clock position is the boiler feedwater preheater. This employs exhaust steam to preheat feed water. 

engine interior

The left side of the engine with the crankcase cover removed. Note the eccentric for the feedwater pump piston. Also, shown is the lubricating oil pump.

open crankcase

The open crankcase from the back of the engine.  The topmost shaft has the water and fuel pump drive cams in addition to the steam cutoff lever. The midshaft has the inlet and exhaust valve cams.  At the bottom is the crankshaft.

steam cutoff

A closeup of the steam cut-off mechanism.  The brass steam cut-off lever and cut-off cams slide in unison on their respective shafts.  The inlet cams are ramped so depending on where the slide mechanism is located, steam is cut off earlier or later.  Cut-offs of 0.2 to 0.8 of full open are possible. 

front closeup

Specifications of the Hubbard Steamcycle

  • Two cylinder, single acting steam engine
  • 3 cubic inch displacement for each cylinder (6 cu in total displacement)
  • Theoretical HP - ~6
  • Transmission - direct drive - roller chain
  • Boiler - triple coil - flash style - superheating loop
  • Operating pressure - 400-700 psi  superheated steam
  • Burner - vaporization style with throttle - alcohol preheating of vaporization coil
  • Fuel consumption - less than 1 gal per hour.
  • Fuel - originally designed for kerosene, also used gasoline
  • Water capacity - ~2 hours with planned condenser

Issues Remaining Prior to Operation Under Steam

  • Boiler was perforated due to rusting during storage.  Must be rebuilt.
  • During initial tests of the vaporization burner in the early 1970's, this key component never operated well on kerosene. Operation using gasoline was inconsistent and hazardous. 

Click here to return to the Photo Essay Page