I was lucky enough to salvage the motor and controller from a free but broken treadmill. After complete disassembly, I discovered that the safety switch was at fault, so I simply bypassed it (no longer a need for it as there was nothing much left of the treadmill to “run” on).
Using some scrap steel shelving, I welded together a simple open box that holds all the treadmill electronics, including the push button control board. This assembly simply sits on top of the shay frame with the wires running out to the motor.
The 2.5 hp DC treadmill motor has a screw-on steel flywheel as it was designed to only run in one direction (driving the running tread forward). Upon digging through a local bike shop’s trash bin, I managed to rescue a used bicycle wheel sprocket which I welded to the flywheel’s hub.
After hearing about my project, the bike shop’s owner was kind enough to donate a used pedal drive sprocket complete with an aluminum hub that fit perfectly on the shay crankshaft. I purchased a brand new chain from him to connect the two sprockets.
The treadmill motor and its adjustable bracket is mounted on a piece of angle iron which is firmly attached to the shay frame using two c-clamps. Lining up the two sprockets is a very simple task.
I squirt lots of oil into the open oil passages while it runs. The oil eventually works its way through the bearings and emerges nice and dark which tells me that the surfaces are breaking in well. I’ve had it cranking continuously for up to two hours with no issues at all.
With the sprocket and chain reduction, I found that the lowest speed setting will turn the crankshaft at around 85 RPM. Pointing a digital laser thermometer at the bearings and engine block journals early during the break-in period indicated that the parts rarely surpassed 25-30 degrees above ambient air temps. Now they regularly run less than 5-10 degrees above normal.
Below is a slow-mo video of it running. The only noise you hear is that of the chain and sprocket!
This break-in method will definitely help keep everything nice and loose as parts are continuously added to the engine. Soon I’ll be running it on compressed air!