c-g-designs

This post is re-edited to day to illustrate a post in 6BR forum.

14 July 2017 (Bastille day..).

A DIFFERENT PERCUSSION SPRING SYSTEM.

            The spring washers or spring disks, commonly named in the industry ‘Belleville Washers’ from their inventor, Julien Belleville constitute an axial compression spring  system delivering important forces  under a small volume but  under a small unit displacement

            Assembled in multiple opposed pairs, the linear displacement  capacity increase the stroke in proportion of the number of pairs stacked, but the load capacity remain those of a single spring washer.

            Just a mention: the Belleville washers can be assembled in multiples, the assembly force being multiplied by the number of washers placed on the same direction, but the stroke  of such assemblies will remain those of a singlewasher.

            In the case of the use of Belleville washers as firing pin  spring, the washers will be assembled  in single opposite pairs, their number being determined by the FP stroke  and the stack height by the number of washers used and their compression height at the desired force.

            The use of Belleville washers allow:

            -A more compact spring : In our example,in the C.G system, the cocked and decocked lengths are, for the coil spring 56 and  60mm respectively while they are only 21,5 and 25,5mm for the Belleville stack.

            --A stronger percussion impact force, adjustable by adding or removing washers.

            --A reduction of the spring  mass. If the coil spring mass is  10,6grammes, while it is only 8,8 grammes for the 43 Belleville washers stack (6,2x12,5x0,35).

            --Moreover, the Belleville, being used only at a fraction of their nominal full capacity they have a  much longer durability than a coil spring used at its full capacity.

            --Finalley, being used well  under full capacity, and at a decocked reduced  load rate,  their regularity and reliability are total. Effectively, their force curve is almost linear, from free height to 75% of their minimal height.

            They correspond to the exigences of a constraining norm (DIN 2093). They are also cheap and easily available.

            Their  superior capacities and reactivity  allow a faster locktime.

            Belleville washers are characterized by:

                        External diameter                         = ’De’.

                        Internal diameter                           = ’di’.

                        Thickness                                        = ‘t’.

                        Free height                                      = ‘L0’.

                        Height under maximal load         = ‘L1’.

                        Load under’ L1’                              = ‘P1’.

            The Rate practically increase in linear fashion between ‘L0’ and ‘L1’. Over ‘L1’, ‘P1’ does not increase anymore. A Belleville washer should never be compressed over ‘L1’.

            In our example; the due to the  flexibility of the Belleville washers,  the use of several references is possible . The one we will use will have the following characteristics:

                        ‘De’ = 12,5mm.

                        ‘Di’ = 6,2mm.

                        ‘t’ = 0,35mm.

                        ‘L0’ = 0,80mm.

                        ‘L1’= 0,46mm.

                        ‘P1’= 155Newton.

            In our case:

--47 Bellevilles will develop 151 Newton (33,3lbs/f).

-45 Bellevilles will develop  144 Newton (31,7lbd/f).

--43 Bellevilles will develop 127Newton (28lbs/f).

--41 Bellevilles will develop  122Newton (26,9lbs/f).

Observations:

            47 Bellevilles will give an excessively powerful.

            45 Bellevilles will give a still powerful impact  and and the fastest locktime.

            43 Bellevilles  will represent the perfect compromise: locktime still very fast and easy bolt lift.

            41 Bellevilles : If the easy bolt lift is preferred, with still a strong impact force and  locktime, both  superior to the coil springs ones (122Newton as against 108 for coil spring..

            NOTE: Philippe Ginestet ,  who have shot and still do, all the C.G models since the prototype 02 of 1985 underline  that the Bellevilles ‘Power Pack’ is totally exempt of vibrations  and become immediately inert  at the   firing instant  and does not generate any secondary noise meaning  detrimental vibrations, contrary to coil springs.  This difference is for Philippe perfectly discernable  in the hearing protection.

            R.G.C

            01-2017