LFRR coupling

Figure 1. LFRR coupling

LFRR Coupling stands for light, frictionless, reciprocating and rotary-motions coupling. It performs the same operation as a crankshaft and a connecting rod do in a piston engine. However, it is lighter, is fully balanced, and (in principle) frictionless.

Formal status


The invention converts reciprocating motion into rotary motion or rotary motion into reciprocating motion. It may be applied in piston engines ot avoid heavy crankshafts and connecting rods; it can also be applied in devices such as air compressors, in which the motion is converted in the opposite direction. When the invention is implemented in a piston engine, it has the following characteristics:

  • connecting rods move only along their axes,
  • a resulting piston movement in the cylinder is with almost no friction,
  • consequently, the piston and the entire balancing mechanism are lightweight, and
  • the engine is fully balanced, it does not even vibrate, even when the engine has only one cylinder.


Components of the invention (see Fig. 1):
1 – engine shaft
2 – arm of first balancing weight
3 – first balancing weight
4 – the axis of the movable wheel
5 – movable wheel
5′ – second balancing weight, part of the movable wheel
6 – center of mass of wheel (5) and its balancing weight (5′)
7 – axis of connection of wheel (5) with connecting rod (9)
8 – stationary wheel
9 – connecting rod
10 – piston
11 – cylinder

Summary of the invention: the movement of the piston (10) causes the wheel (5) to rotate simultaneously about its axis, and about the axis of the shaft (1), the movement of the wheel (5) around the shaft (1) rotates this shaft. When the moving wheel (5) has half the number of teeth as the stationary wheel (8), and some trivial geometric relationships are preserved, then the axis (7), together with the connecting rod and the piston, move precisely along a straight line. Therefore, the piston can be rigidly connected to the connecting rod. Therefore, it can be lightweight and the balance weights can accordingly be lightweight. In addition, the piston moves in the cylinder with virtually no friction, which makes the engine efficient.

Figure 2 below shows the subsequent phases of the engine movement.

Figure 2. Subsequent phases of the engine movement

Other variations with the design introduce further amenities. In particular, the mechanism is fully balanced when the piston and the weights move in the same plane, which can be easily achieved by giving the components the appropriate shape.

Formal status

A patent for this invention is pending.