Tappet/Clapper Valve steam engine

[The_Paso_Kid]

My grandfather had attempted to build the tappet valve engine by Graham Anderson, see attachment, several years ago. I assisted him with some of the machining. However we were never able to get the engine running. He threw it in a box and it has been stored ever since.

He recently decided to try the Clarence, a Clapper engine. Again I've machined a few parts for him. We have just assembled it and tried it on air without any success.

Not sure what we are doing wrong.

Anyone have any suggestions on either of these two projects?

 

[The_Paso_Kid]

This is our version of the clapper valve engine using materials we had on hand.

 

[IanN]

Hi,

What pressure are you running the air supply at?

It the pressure is too low the engine cannot run and if it is too high it cannot run.

Taking the "too low" case first:

As the system is a 'uniflow' design the rising piston must compress the air in the cylinder - the compression required being roughly the ratio of the free volume of the cylinder when the piston is at TDC to the free volume of the cylinder with the piston crown just covering the port.

The stored energy in the flywheel must be sufficient to provide this compression.

The stored energy comes from the admitted compressed air. Assuming no losses, and ignoring the energy required to open the 'clapper' valve, the admitted air must be at the same level of compression in order to give the flywheel the required energy used in the compression stroke.

As an example, if the compression due to the rising piston is 4:1, then the engine cannot possibly run on an air supply less than 60PSI

At the other end of the spectrum, the flywheel must have sufficient stored energy after completing the compression stroke to overcome the pressure on the 'clapper' valve due to the air supply - the energy stored is a function of the flywheel mass, dimensions, shape (polar moment of area) and angular velocity, while the energy required is a function of the valve plug cross sectional area and the air supply pressure. If the air pressure is too high the flywheel will not be able to achieve the angular momentum required to overcome the force holding the valve closed.

In short - try playing with the air pressure. Start low and slowly increase the pressure until the motor runs

All the best,
Ian

 

[Shipdisturber]

Based on the mechanism air or steam will hold that ball seated, the tip of the piston has to unseat the ball to allow air or steam to enter the cylinder, compression won't do it. The stopper above the ball needs to have enough clearance to allow air or steam around it, also the stopper can block the entrance for air or steam to enter. If you replaced the block with a spring it will work fine as long as the spring isn't too aggressive.