Thanks HV. You spotted that one right. It's a bearing on the outboard end of the shaft so the motor bearings don't get all the load. Blain's Farm & Fleet sells them for 8 dollars. Here's some new pics to show it better.
The bearing pillow block is bolted in the black angle which bolts to the "pivot shaft" which runs through mounts on the seat stays of the frame. So the motor and outboard bearing pivot up and down together when I engage/disengage the drive.
The friction wheel I prefer to use (on the bike now) was made from a hockey puck. A hockey puck is 3" diameter and 1" thick. With hole cutters, I cut out a wheel 1 1/4" inches diameter and drill a 7/8" hole in the center. I can get 3 drive wheels out of one puck, but my first one has lasted a year with little wear.
So then I epoxied (clear 5-minute epoxy) it onto a steel spacer. I bought the spacer (that's the actual name of the item) from Lowes hardware section. It's 1 1/2" long, 7/8" O.D., 5/8" I.D. and fits over my 5/8" motor shaft. I drilled and tapped two holes for set screws.
The one that I am holding in the picture (grit wheel) is basically made the same way except the material is a urethane skateboard wheel. Urethane (Gorilla) glue is used to glue the wheel to the spacer and the grit on the wheel. Epoxy don't stick to the urethane good at all, but Gorilla Glue sure does. The grit is from some weird old grinding wheel I got somewhere about 20 years ago. It is "friable"; the grit breaks off of the grinding wheel easily. It is white and rather sharp and glass-like.
The grit wheel works well in wet weather, but I can notice more tire wear than the dry-weather, hockey puck wheel.
The bearing pillow block is bolted in the black angle which bolts to the "pivot shaft" which runs through mounts on the seat stays of the frame. So the motor and outboard bearing pivot up and down together when I engage/disengage the drive.
The friction wheel I prefer to use (on the bike now) was made from a hockey puck. A hockey puck is 3" diameter and 1" thick. With hole cutters, I cut out a wheel 1 1/4" inches diameter and drill a 7/8" hole in the center. I can get 3 drive wheels out of one puck, but my first one has lasted a year with little wear.
So then I epoxied (clear 5-minute epoxy) it onto a steel spacer. I bought the spacer (that's the actual name of the item) from Lowes hardware section. It's 1 1/2" long, 7/8" O.D., 5/8" I.D. and fits over my 5/8" motor shaft. I drilled and tapped two holes for set screws.
The one that I am holding in the picture (grit wheel) is basically made the same way except the material is a urethane skateboard wheel. Urethane (Gorilla) glue is used to glue the wheel to the spacer and the grit on the wheel. Epoxy don't stick to the urethane good at all, but Gorilla Glue sure does. The grit is from some weird old grinding wheel I got somewhere about 20 years ago. It is "friable"; the grit breaks off of the grinding wheel easily. It is white and rather sharp and glass-like.
The grit wheel works well in wet weather, but I can notice more tire wear than the dry-weather, hockey puck wheel.