Frequently Asked Questions
What is the S-RAM?

"S-RAM" stands for "Sanderson Rocker Arm Mechanism", and is an elegantly simple new drive mechanism to convert reciprocating to rotary motion and vice versa without the energy-robbing side forces on the pistons or crosshead common to crankshaft, swash plate or wobble plate systems.  The S-RAM can vary the piston stroke while maintaining a constant head clearance.  The S-RAM can also be configured with opposed pistons resulting in incredible power density.

What are the main S-RAM technical advantages for engine applications?

The S-RAM has five major technical advantages as compared to crankshaft engines and pumps:

(1) The S-RAM replaces the crankshaft assembly, thus most of the bottom-works of an engine can be eliminated.

(2) The S-RAM dramatically reduces engine friction piston/cylinder sidewall friction and overall bearing friction. The S-RAM zero side load (ZSL) joint creates a straight-line piston motion within a cylinder almost eliminating piston sidewall friction. The S-RAM has approximately 50% of the number of bearings and, ⅓ to 1/6 the bearing surface speed, resulting in an overall bearing friction that is less than 20% of that of a crankshaft engine.

(3) The S-RAM can vary piston stroke, and therefore, an engine designer can create a Variable Displacement and Compression Ratio (VCR) engine.

(4) The S-RAM changes the form factor of an engine and allows the use of an axial or barrel engine configuration providing an engine designer greater freedom. The S-RAM axial geometry creates a cylindrical package, allowing for a wide range of applications that have limited space or unique installation requirements.

(5) The S-RAM can be built with "double-ended" pistons without adding much space. The S-RAM can easily drive a mirror image rod and piston in the opposite direction 180 degrees out of phase. The performance of an engine or pump can essentially be doubled without adding much weight or size.

Why do you call the S-RAM an "elegantly simple" mechanism?

The S-RAM is a new way to move pistons using readily available and proven components and does not require any changes to the design of pistons, piston rings or cylinders. The S-RAM is compatible with any above the piston valving, injection or combustion systems, and therefore, provides the engine and pump designer with design flexibility.

How do you balance the S-RAM?

Balancing the S-RAM was a recurring problem in the early stages of the S-RAM technology but has since been solved, patented and tested.  The motion of the S-RAM is very nearly sinusoidal and the harmonic components are unusually small.  The secret of balancing the S-RAM is in the way the pistons work as a unit.  Taken one at a time, it would not seem possible to balance the mechanism.  However, any number of pistons three or greater and evenly spaced are easily balanced.  We can now achieve near perfect balancing of the S-RAM.

Can the S-RAM be scaled up to very large engine and pump applications?

S-RAM scalability is similar to that of the crankshaft mechanism in that no scaling problems arise that grow as the square or higher power of the linear dimensions.

What prototypes have you built and tested?

We have designed, fabricated and tested seven pump, engine, compressor and engine prototypes.  We have had excellent test results that have resulted in continuous S-RAM improvement.

What are you doing to further develop the S-RAM technology?

We are currently designing and building four major S-RAM prototypes: the S-RAM Semi-Free piston engine for stationary and mobile power applications, a mechanically modulated variable compressor, an expander for a new waste heat engine (using hybrid Stirling cycle) and a reversible hydraulic motor/pump. The objective of each prototype project is to demonstrate how the S-RAM drive mechanism can substantially improve machine performance.

Will you license the S-RAM technology?

Yes.  We will license the S-RAM drive technology for engine, pump, compressor and expander applications.  Our engineers will first determine if the S-RAM will provide you a competitive advantage and then we will engineer the S-RAM for your application.