# Using Elliptical trammel for opposed cylinder engine

• Automotive
• The tin man
The tin man
Question I'm sure theirs a reason this hasn't been done but why couldn't you use an elliptical trammel as a design for an opposed combustion engine where 2 cylinders are vertical and 2 horizontal and have the cylinders combust in separate loops wouldn't that technically do the same thing in principle as long as the pressure fed in a loop

Welcome to PF.
You could use an elliptical trammel in a four piston engine.

The reason it is not done is probably because of bearing lubrication problems, due to high surface velocity.

The engine would be more compact if it was built as a flat boxer, with a quadrature crankshaft for the two journals.

Maybe a diagram of your idea would help find references to that style of engine.

I think balancing the assembly at high speed might be difficult as the two cylinders would need to be offset (and the crankshaft as well). Or you would need multiple two-cylinder trammels to balance each other?

Otherwise, it would look a lot like a radial engine with fewer pins needed. In the following animation, the link with the 5 pins would be the rod between the two pistons; The middle of that rod being connected to the crank pin.

(original animated GIF)
I also found this but I have no clue what the engine looks like.

Last edited:
Without a closely coupled flywheel, the four piston engine would need to be of two-stroke design.

Four-stroke radial engines need an odd number of cylinders, usually greater than six.

## What is an elliptical trammel and how is it used in an opposed cylinder engine?

An elliptical trammel, also known as a trammel of Archimedes, is a mechanical linkage that generates an elliptical motion. In the context of an opposed cylinder engine, it can be used to convert the linear motion of the pistons into a smooth elliptical motion, which can then be harnessed to drive the crankshaft or other components of the engine.

## What are the advantages of using an elliptical trammel in an opposed cylinder engine?

The primary advantages include smoother operation and reduced vibration due to the balanced nature of the elliptical motion. It also allows for more efficient conversion of linear motion to rotational motion, potentially improving the overall efficiency of the engine.

## How does the elliptical trammel impact the performance of an opposed cylinder engine?

The elliptical trammel can enhance performance by providing a more continuous and stable transfer of energy from the pistons to the crankshaft. This can lead to better fuel efficiency, reduced wear and tear on engine components, and potentially higher power output due to more effective energy conversion.

## Are there any specific design considerations when integrating an elliptical trammel into an opposed cylinder engine?

Yes, several design considerations are crucial, including ensuring the trammel is precisely aligned to maintain the elliptical motion, selecting materials that can withstand the mechanical stresses involved, and designing the trammel to fit within the spatial constraints of the engine. Proper lubrication and maintenance are also essential to ensure longevity and reliable operation.

## What are the potential drawbacks or limitations of using an elliptical trammel in an opposed cylinder engine?

Potential drawbacks include increased complexity in the engine design, which can lead to higher manufacturing costs and more challenging maintenance procedures. Additionally, if not properly designed or maintained, the trammel mechanism could introduce mechanical inefficiencies or become a point of failure in the engine. Ensuring precise alignment and durable construction materials are critical to mitigating these issues.

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