Sunday, February 16, 2014

The Adams-Farwell: An Early Radial Automobile Engine Design

A reader sent this to me.  I am still a bit confused how this can work: the crankshaft is stationary, and the radial cylinders move!  If the crankshaft is stationary, how does it impart motion to the wheels?  Still fascinating.

9 comments:

Jim Dunmyer said...

These engines were fairly common in the early days of aviation, but became obsolete by the 1920s. See: http://en.wikipedia.org/wiki/Rotary_engine

The power takeoff is from the [spinning] crankcase

The Wikipedia article gives the details, including advantages (cooling, smooth running) and disadvantages (many).

Jim said...

The Sopwith Camel in WWI was similar. The crankshaft was stationary and the engine rotated around it. It's very odd but when you think about it, it's all relative. Normally, the engine is stationary and the crankshaft spins. This is just the opposite. Of course there will be a lot of rotating inertia so accelerating (both positive and negative) will be slow.

bombloader80 said...

This type of design was also called a rotary (not to be confused with the Mazda rotaries which are Wankel engines.) It was pretty common in aircraft engines thru WWI. It fell out of favor between the wars due to it's complexity.

Chaplain Tim said...

Power transmission would be the same as early rotary aircraft engines. The crankshaft is stationary, allowing the pistons and crankcase to rotate. On an aircraft they'd attach the propeller to the crankcase, so Mr Allen must have connected the driveshaft to the crankcase (not the crankshaft like a normal engine).

Rob K said...

That thing is kinda terrifying. I can think of a lot of things that could go catastrophically wrong with one of those, that wouldn't be a big deal on a normal engine.

w said...

As I recall the problems with rotary engines is max horse power and power to weight ratio--heavy engines relative to low horse power. As airplanes got heavier they just couldn't cut it--not enough power. They hit a limit with it fairly early on for aviation. Radial engines allowed for the similar cylinder placement (as opposed to inline cylinders) which had some of the cooling advantages. Radials were very costly to work on though.

Balance is very critical for these engines as others pointed out. All that mass rotating and hitting road bumps, etc (remember early roads were mostly unpaved). Just wasn't practical in the long run.

Near the end of the video of the underside is shown and it appears there is probably some gear attached to the bottom so as it rotates it provides the drive energy (hidden by a cover). Presumably there is a clutch mechanism to engage to a transmission. It does look like the actual energy to the rear axle comes from a chain. At least a chain is visible but since the vehicle is in neutral it isn't turning. Chain drive was common on those Jurassic vehicles.

Nevertheless way cool!

Fidel said...

The biggest problem with these rotary engines was the incredible torque during take-off and acceleration, making it very difficult for inexperienced pilots to fly.

In a car though, I can't imagine any value.

Minicapt said...

The horizontal engine is mounted to the engine mounting frame via the fixed crankshaft emerging out of the crankcase 'top'. The 'bottom' of the crankcase has a 90deg bevel drive to the transmission. The underside of the engine is at 4:18 minutes.
http://airandspace.si.edu/collections/artifact.cfm?id=A19130001000

Cheers

Windy Wilson said...

It's my understanding that the US M3 Stuart light tank used a radial engine. The next model, the M5, used twin water cooled Cadillac V8s.