Member postings for Four stroke Fred

Thanks for the comments from those who are following the progress on this model and good to hear that you are making a Diesel engine Roger ( what is it?) They do present a real challenge but that’s what makes life interesting. The Mc Donald did not use a cartridge type start. The flywheel has a retractable sprung loaded handle and the engine is “ rocked” until it bounces of compression and fires up. I hope the model will do the same but I expect there will be teething problems and I will just have to try to solve them one at a time.

Fred

Good Day Bill,

I have an original casting for the Sugden Special that I have had in store for at least fifty years and would be willing to part with it! I had intended to make it but at that time I had neither the skills or equipment and yes I live in Australia.

Fred.

This shows the pre combustion chamber and the hot bulb with its special peg spanner. The castings still have to be cleaned up and made presentable.

Fred.

This photograph shows progress so far on the cylinder head with the 3D printer pattern on the right and the real part on the left. The larger of the two holes on the front is for the decompressor valve and the hole below is for the escaping gas. The recess on the left is for a glow plug and yes this was fitted to the full-size tractor and used in cooler climates to help with the starting. In some cases they may have used a spark plug and a trembler coil to provide a cascade of sparks. I will also post a photo of the combustion chamber and the underside of the head/ hot bulb. The bulb is detachable and I may have to experiment with lengths and thicknesses but that’s for later.

Fred.

Good Day Roger
Thanks for your comments. On the full size tractor there is a place for a plug ( glow or spark) and I have incorporated this in my model and is the hole on the left hand side of the cylinder head. I was told these were used for the starting process in places where the climate is cooler and it is harder to keep the bulb hot. I can fit a 1/4 x 32 commercial glow plug and may use that for initial testing.

Fred

These are the 3D drawings of the cylinder head with the injector on the top and the hot bulb on the under side. The top photo shows the hot bulb and special peg spanned and the lower part of the combustion chamber all made from steel.I may need to experiment with more hot tubes of various thicknesses and lengths but will have to wait until the rest of the engine is made to test what will actually work. The match box gives some idea of scale. The next stage is to make 3D patterns for the main part of the head and then cast them in aluminium.

Fred

Thanks for your comments. After all this time and effort there is no guarantee that it’s going to work but it’s good fun trying and a great learning process.

Fred.

This is the injector pump with the cover removed to show what is happening inside. The brass fittings are one way valves that allow fuel in from the tank and then pumped out to the injector nozzle. As the cylinder is almost horizontal gravity is used to seat the ball valves with small 12 BA pins used to prevent them from “ jumping” to far off the seat similar to the check valves used on model steam locomotives.The handle on the right controls the amount of fuel being pumped to the injector and is connected by levers to the drivers end of the tractor. The knurled part holds an “O” ring in place to help form a seal between the 1/8” piston and cast iron cylinder. I now have to start to think about the cylinder head and that will be a really interesting part to design and make but that for next week!

Fred.

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The photo shows progress this week and it doesn’t look like very much! It’s what you can’t see that has taken the time as it all happens behind the bob weights. I have made and fitted the cover and added various parts.The injector plunger that activates the pump can be seen protruding from the the top and on the left is the arm that operates the oil pump. Further to the left is the inspection hatch that enables the governor springs can be adjusted. Having drawn all these parts they were then 3D printed to give an idea of the full size model parts. The drawing of the parts on the screen gives a false impression of size but having them in your hand is reality. The injector pump and valves will be the next part to be made as weather condition have halted any attempt to make castings ( we work in the open air).
Just a few facts on our weather that may interest you - parts of the east coast of Australia has been hit by a band of very heavy rain but fortunately most of it has missed our area. One Queensland river rose 25 metres, another place had 700 mm in one day and we had hot steamy nights with 27C being recorded at 3.0am! We are looking forward to cooler and drier times.

Fred.

The photographs show progress on the governor. I still have to add the spring adjusters and test to see what speed the cast iron weights throw out to the outer limits. The eccentric is made from bronze and will have a steel eccentric sleeve/ rod when it is made. Having studied the injector pump arrangements on the Lanz I now understand how it works - the outer eccentric gives the pump stroke and the inner concentric one gives the advance/ retard but I have made mine as shown on one of the sets of drawings for the Mc Donald. If I find after test this does not work I will have to change the design. The reason for choosing this is because there is very little room for two eccentrics and there are less parts to make! The next part to make is the injector pump.

Fred.

Thanks for the information Roger all very useful. I forgot to mention that the button on the front of the flywheel is the starting handle that springs back into the position shown when not in use.

Fred.

One flywheel completed and as you can see it is heavy and should give plenty of momentum to the engine and hopefully help it to run slowly. I now have to go back to the injector cam and think that through. I was pleased to hear that there is a little flexibility in the actual timing of the injected fuel. I have two drawings of the system and think that one may be a later development but as I can’t take the full size tractor apart I will have to choose the one that suits me! The one I originally designed allows the bob weights to move the eccentric via two linkage arms thus giving and advance/ retard but keeping the ‘ stroke’ constant. The fork alters the quantity of fuel to be injected but would slightly alter the timing as there is gap between contact of the ram on the eccentric and the fuel piston. The wedge shape on the Lanz avoids this. As these engines will run in the reverse direction ( more by accident than choice) does the governor advance the injection point before top dead centre? More thinking required!

Fred

Roger you are correct. Today I used a magnifying glass to look closer at the drawing I have been using and can just about make out that the system on the Mc Donald is very similar to the Lanz in that the governor moves a secondary bearing inside the eccentric. Thanks for your help, much appreciated.

Fred.

Thanks for the information Roger. The system shown for the Lanz may be the same as used on the Mc Donald but on the information I have does not show it clearly and I may need to revise the system on the model. The Mc Donald was based on some of the Lanz technology - more research and study required! Fortunately I have not started to make this part of the model as yesterday I made the flywheel. It is now reaching the interesting stage of the model
- the injection system and cylinder head. Plenty to think about.

Fred.

Roger this diagram may help to explain how the system works.

Fred

Good Day Roger,

The bob weights throw out and cause the eccentric ( constant stroke) to rotate backwards and this alters the point of injection but not the volume as this is controlled by a forked lever that alters the length of the stroke of the piston. I will show a drawing of this set up when it has been developed.

Fred.

These are the parts that make up the injection system. The top view shows the bob weights that throw out and are connected to the eccentric by pins - springs and pins have been omitted. The lower picture shows the eccentric and rod - the small bar on the top is linked to and drives the oil pump. Apologies for the strobe effect from the screen.

Fred.

Thank you Dom and Derek for your comments and it’s good to know that this saga is being read and enjoyed. It has been going for quite some time and there is still some way to go. Yesterday was spent finalising the injector pump mechanism design and today I will prototype some of the parts on the 3D printer. The eccentric that drives the pump has a built in advance retard activated by bob weights.This changes the point of the injection and acts as the governor ( we hope) but some experimentation will be required in the initial set up. The whole of this unit sits behind the flywheel that has yet to be made. This part of the project is a challenge but that’s what makes life interesting!

Fred.

This weeks effort saw the completion of the brake/ clutch unit. Although the brake part is small it was not straight forward to make and fit and it took three attempts to bend the steel arm to shape and machine the hole at the angle required. The cheese head screws will be replaced with hex head bolts of the correct proportions. I am now looking forward to working on the other end of the crankshaft and making the flywheel and the injector cam that incorporates and advance retard mechanism.

Fred.