Engine valve actuating mechanism, showing concentric compression springs. The use of concentric springs, two or at times three together, can provide greater force and stiffness in a given volume. Springs and couplings - Andrei Lozzi

The use of numeric optimising software have shown that the more compact designs for concentric springs divide the load 90% - 10% between the outer and inner spring. Or equally effectively: between the inner and outer. There seems to be two solutions, the solver stops at the nearest one from the starting condition. 2

A huge variety of designs of steel springs have been used to return engine poppet valves to their seat. At right a pneumatic cylinder is used instead of a steel spring. This springing medium can provide a greater force than a steel spring can in the available space, thereby permitting greater engine rpm and more power for an engine of a given size and mass. 3

A carriage suspension system showing the use of concentric springs 4

In limited space it is more efficient to use a large number of small concentric springs in place of a few large spring. Large springs have large voids associated with them. 5

The more conventional division of force between outer and inner concentric springs has been typically about 70% for the outer and 30% for the inner. The springs shown above is a rare example seen where the 90% - 10% division seems to be applied 6

The Orlov synoptic spring chart, used prior to the advent of ‘optimising’ software 7

8

Calculations begin with selection of the working stress (4000 kg/cm 2 ~400mP) at 1, ends with deflection per coil at 5, 1.5 to 7 mm per coil, for spring indices of 5 or 10 9

A new and novel type of engine valve springs that claims about 12% improvement in height and mass, is shown a near left. This spring uses wire of almost an elliptical section. A traditional assembly of two concentric springs, of comparable properties to the new spring, is shown at far left. 10

The ovate section of the wire used in this novel spring 11

The graph at left shows the residual compressive stresses plotted against depth, that exist in the wire of a spring that has been shot peened. 12

13

Some modern valve springs. Concentric – different wire dia. Variable stiffness 14

An unusual spring, cut from solid, using a wire Electrical Discharge Machine (EDM). 15

16

17

General view of a Panzer Bike, imagine one could have a Ducati instead ! 18

The rear, not the front, has a variable rate suspension spring, maybe to meet the needs of geriatric riders. 19

In the present desire to make lighter, more efficient and higher performing cars, exotic material like titanium is been considered for even ‘normal’ cars 20

Split tapered coupling can be used in pairs, between cylindrical shafts and housings. May be clamped together by internal or external screws 21

A fluid coupling and an example of a possible variation referred to as a torque converter. 22

Complete self contained industrial fluid couplings are available to multi mW capacity, of about 1500 mm diameter 23

24