5 cyl OHC Radial.

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Brian40

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Time to be thinking of the next engine, so after lots of doodling on scraps of paper and the computer I have come up with this offering.

Five cylinders 25mm bore X 28 mm stroke. with overhead camshaft

Must be able to be made on a 7X12 and a small mill.

I think this will keep me occupied for two to three winters.

Brian.

Drawing.jpg
 

Swifty

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Bevel gear drive on the overhead cams? Like Ducati engines.

Paul.
 
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Brian40

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Hi Paul
Nothing so sophisticated one to one spur gear to get clear of the crank then MXL 2 to 1 belt to the cam. ignition to be driven off one of the cams. the gear case is the next area to be drawn up.
I am trying to design this as easy to make as possible.

Brian.
 

Brian40

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The gear case and drive to the camshafts looks fit to go to the next stage.so its on to the crank shaft and auxiliary drive.
Now Paul you can see how the drive for the cams is arranged.
A casing over the belt drives will take the drives for the two oil pumps from the two lower gears.
I intend to split the ignition between the cam shafts No's 2 & 5 a magnetic trigger on 2 and distributor on 5.
A long way to go yet even for the general layout.
Brian

Gear case side view.jpg


Rear View.jpg
 

Swifty

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Looks great Brian, will the belt drives be on the front or rear of the engine. I was only thinking that if the drives were on the front and you had covers on them, it would impede the cooling of the engine, that's if you had a prop on it.

Paul.
 

Brian40

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The belts are at the rear of the engine Paul the gears are inside the rear of the crankcase.

Brian
 

Swifty

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I should look at your drawings a bit closer next time, it is quite evident that the belts are at the back.

Paul.
 

Brian40

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Things are moving on in the doodle department,
The cover over the cam drive belts has been extended to form a mounting for the engine and the oil tank, the oil pumps are now inside the tank and driven from accessory shafts 2 and 5.
A annular duct in the nose piece forms part of the inlet system taking the mixture from the propane gas carb underneath the casing and passing it up to the heads.
The cylinder length and rod length has been has been increased to reduce rod angularity and allow for a better master rod.
The slow process of changing the idea into working drawings is underway.
The side view drawing is a montage of all the cylinders showing all the features on the one cylinder The only component missing is the trigger unit that will be on cylinder No 5, But it gives the general idea.
Brian.

Side view long 2.jpg
 

Brian40

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Over the past few weeks the design has changed quite a lot as I started to do working drawings. the barrels are now steel ---crank case larger---shorter stroke---coaxial oil pump. ETC
So now At last the first chips are flying.
First part to be made is the Jig that all of the crank case parts will be made on.
All the registers on the crank case are the same diameter and the jig will be
transferable between the rotary table and the lathe face plate.

The blanks for the jig only just fit the chuck so off we go on the start of a long journey.

Brian.

P1013123.jpg
 

Brian40

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It's been head down for a few weeks while I have been working on the jig's the case jig has a female register to locate the case and a adaptor ring to convert it to male so the opposite side of the case can be machined. as all the registers are the same diameter I think this will keep it all in line. with the R T vertical I can machine the cylinder locations on the same jig.
the second jig takes the cylinders and heads. the jigs can be used on either the lathe or the mill.
Brian.

P1013132.jpg


P1013133.jpg


P1013135.jpg
 

jimjam66

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Lovely work, Brian. Looking forward to more progress!
 

Brian40

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Hi David .thanks for your comments, most of the progress at the moment is in the paperwork !!! getting from a concept drawing to working drawings with real dimensions that do not conflict with each other takes a long while,
but I am getting there slowly. regards Brian.
 

kf2qd

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That master rod doesn't look quite right. Did you figure the pin location with the crank at TDC for each cylinder?

Because of the motion of the master rod because it is tied to cylinder 1 it is out of time on the others.
 
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Brian40

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This is the reason for OHC valve and ignition timing is independent.
Brian.
 

kf2qd

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But individual cylinders will be hitting TDC at angles other than every 72 degrees and that will add vibration. By adjusting the position of the slave rods in the master rod the engine will run smoother.

Copying the jpeg you posted into autocad as a raster image and then rotating around the crankshaft I come up with 85 degrees and 152 degrees for the angle of the slave holes from the master rod. Longer rods in larger engines require less of an offset.

Here is a quick sketch I drew up based on the images you posted earlier. The red circles are for a master rod with the holes 72 degrees apart, and the small green circle is the shift to give TDC at 72 degrees of crank rotation. for the 2 upper side cylinders I come out with an 85 degree offset, and the lower 2 with 152 degrees.

 
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Brian40

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OK my original thinking was that tdc being a few degrees out was not going to matter if the timing was right.
after all we live with V twin engines and offset vertical twins.
However I am always willing to learn. so am I correct in thinking that 85° refers to cylinders 2 and 5. and that 152°
refers to 3 and 4.
next problem is that the drawing you used is out of date the stroke has been shortened and the cylinder lengthened ,this was done to reduce the angularity of the slave rods, the drawing now looks like this.
Brian.

img121.jpg
 

kf2qd

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Here is what I come up with -

This is based off the image files. Would be more accurate from a cad file.
Slave rods are the same length.

 
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Brian40

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I have drawn out the layout and come up with 83° and 151°
I will redraw the master rod and see what and see what it looks like.

Brian.

img123.jpg
 

Brian40

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OK the time has come to start I have ordered the steel for the cylinders.. so its heads down for the log haul,
I think this one is going to take about three years.
No doubt we will have problems to solve along the way I know that getting the crank balance is not going to be easy there is so much advice and it's all different. that I am considering dynamically balancing it ?? so that will mean making a triggered strobe , oh well just another job.
Brian.
 
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