Simple crankshaft bearing.

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100model

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I think most model engine builders start with a oscillating single cylinder engine because it is so simple to build, only three moving parts. I then had the burning desire to build a multi cylinder engine and settled on a three cylinder radial oscillating engine. I started to look at ways to connect the three pistons to to the crankshaft and was not happy with the forked bearings to keep the port faces in one plane. This was 22 years ago so I had a look at the internet and found a drawing about slipper bearings on a peter brotherhood thee cylinder radial engine. Sadly I have lost that link but I made a video showing how it works. Single cylinder engines tend to vibrate a lot but three cylinder engines are very smooth running engines so if you want build a multi cylinder engine this is the one to build. The bearing was cast in bronze and cut into three pieces with a hacksaw. As they move independently on the crankshaft a bit of trial and error was used to to trim away metal so they did not collide with each other. These days a cad model could be used to arrive at the correct shape.

 

LorenOtto

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What an elegant solution! My first engine build 40 years ago was a very simple 3 cylinder oscillator with simple sheet metal connecting rods that had to be bent to eliminate interference.
 

Lloyd-ss

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Nice! The dithering of the individual cylinders is very interesting to watch, especially at slow speed, kind of mesmerizing. Clever bearing solution. I assume the cylinders are single acting, pushing, with no pulling?

In your first sentence where you say you "had a burning desire" I knew all was lost, and there would be no stopping you, ha ha. :eek:
 

100model

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Nice! The dithering of the individual cylinders is very interesting to watch, especially at slow speed, kind of mesmerizing. Clever bearing solution. I assume the cylinders are single acting, pushing, with no pulling?

In your first sentence where you say you "had a burning desire" I knew all was lost, and there would be no stopping you, ha ha. :eek:
Yes you are correct they single acting and it is such a joy to watch running.
 

Nerd1000

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Unconventional, and very cool!

Why did you do this rather than a master/link rod arrangement like on a radial engine?
 
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I do like your application of the slipper bearings, and youn obvious skill in foundry work and machining.
But: When you say "These days a CAD model could be used to arrive at the correct shape." I think you mean that a bit of simple geometry and calculation will define the shape of the slipper bearings. Just 120degrees minus the swing of the oscillating cylinder (The swing is twice the small angle within a triangle of hypotenuse = the centre of cylinder to centre of crank distance, short leg = half the stroke and then add a few degrees for clearance, or plot it properly with a compass pencil and ruler if you can't do the sums? From a simple picture you can measure the angle with a protractor.
CAD is just a computer doing the drawing and calculation after you have done the real thinking, so isn't necessary IMHO?
K2
P.S. For those who want the maths... read on, for those who don't, just ignore this bit.
The swing is 2 x t, where t is the angle defined by sine t = crank radius/distance between centres.
If crank radius = 1/2 inch, (1 inch stroke of piston),
distance between centres = 3 inches (centre of crankshaft to centre of rotation of cylinder)
Then sine t = 0.5/3 = 0.1667:
to the angle t = 9 and a bit degrees, just about 10 degrees.
So, 2 x t = 20 degrees, plus a couple of degrees for clearance = 22 degrees. This is the amount to be removed (half either side) from the 120degrees of the "cut" bearing. I.E. the bearing made to just (120-22) degrees = 98 degrees will be OK and have adequate clearance.
Incidentally, many machinists use Sine bars to generate angles for setting pieces for machining, so I trust I am not being "too complicated" in this post? - K2
 
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Hi D & D, I guess when you talk of the British Anzani engine, you mean a 3-cylinder radial engine configuration,
NOT this:

Or these:

but this?

There are many configurations made by this eminent engine maker of a long history.
British Anzani Engine Co
Anzani of Middlesex
Anzani was an engine manufacturer founded by the Italian Alessandro Anzani (1877-1956). The company produced proprietary engines for aircraft, cars, boats, and motorcycles in factories in Britain, France and Italy.

In the UK, British Anzani outsourced the manufacture of their engines to Coventry Ordnance Works. In the 1920s it was refinanced as British Vulpine Engine Co and then again as British Anzani Engine Co concentrating on small engines and car and motorcycle powerplants.

They supplied AC Cars with the 1,496cc side-valve four cylinder (that would become their famous 2-litre motor), Frazer-Nash with an 1,496cc ohv engine, Morgan with a V-twin, and Squire with the R1 twin cam engine. Their most well known products came to be in motorcycles, lawnmowers and outboard engines.

The following manufacturers employed British Anzani engines (and derivatives):

AJW
Cotton
Croft Cameron
Greeves
McEvoy
Montgomery
Morgan
Norman
NLG
OEC Motorcycles
Tandon
Tornado
Trump


In later years the company diversified and as the British Anzani Group it finally went into liquidation in 1980.

Timeline
1927 Private company.
1937 Formed as a private company
1937 Aero engine manufacturers.
In 1939, British Anzani built a prototype that was the forerunner of the popular post-war clip-on model. Simple in construction, it was a 61cc two-stroke that was positioned beside the left upper chain-stay with the cylinder inclined along the frame tube. Ignition was by magneto and a petroil tank sat beside the drive roller. The firm was unable to develop the idea due to other commitments.
1951 Became a public company
1961 Employs 150 persons. One of the largest manufacturers of outboard marine engines. Also make 'Easimow' motor mowers, power units for motorcycles and light cars and 'Astra' light utility vehicles.
Thanks for your post, it prompted me to read up about them. I enjoyed all that!
K2
 
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