Thanks everyone for the supportive comments!
When the time comes, I will start a separate thread for the donated Carette engine.
In the meantime, back to our regularly scheduled program...
CRANKSHAFTI hadn't originally planned on doing anything with the crankshaft. There was considerable wear in the bearings, which is odd, since they are fairly wide, and are equipped with nice oil cups. Then again, I suppose just having oil cups provided doesn't mean they will always be used.
In addition to the worn bearings, the flywheel had a quite noticeable wobble, as though it had been impacted at one time or another. Neither of these faults would keep the engine from running, nor were they even visible at a casual glance. But since I had the engine apart, I figured there would never be a better time to address these issues.
Here's a "before" shot of the crank assembly. The shaft is a fairly simple affair. It has a diameter of 4.5MM, and the business end is turned down and threaded for the crank. The bearings are integral to the engine frame casting:
[ Guests cannot view attachments ]
Here's a close-up of the crank/eccentric mechanism. The crank is threaded onto the end of the shaft, against a spacer. The eccentric rides on this spacer, and has a radial slot. A small screw in the crank engages this slot to impart motion to the eccentric, while also allowing the engine to run in either direction:
[ Guests cannot view attachments ]
The flywheel end of the crankshaft assembly features a small, knurled pulley to drive the governor, held in place with a tiny setscrew. An outboard spacer keeps the flywheel clear of the engine base:
[ Guests cannot view attachments ]
How is the flywheel attached to the shaft, you may ask? I wondered too, as there was no setscrew provided, for either the flywheel or the accessory pulley. I assumed these items were simply pressed onto the shaft, as were the flywheels on the two Empire engines I worked on recently. As I would later find out, the flywheel and pulley are actually
threaded onto the end of the shaft. This is something I'd never encountered, and it kind of threw me for a loop. Here's a shot of the crank shaft, now "liberated" from the remainder of the engine:
[ Guests cannot view attachments ]
Right off, you may notice that there is very little, if any, wear in the bearing areas. Most all of the excess clearance is in the bearings. I'm not crazy about how the designers chose to mount the flywheel to the shaft. Necking down and threading the shaft creates a
stress riser at the interface between the threaded portion and the cylindrical part of the shaft; a weak spot, and an open invitation to bending stress. I decided to make an improvement by eliminating the thread on the new shaft, and mounting the flywheel with a slip-fit, and setscrewed to a flat on the shaft.
(more to come...)
Home
Search
Today's Posts
Login
Register