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Villiers Dynastart Sales Leaflet

The SIBA Dynastart has been developed over a number of years and is an entirely novel design of combined starter motor and dynamo for use with motor cycle internal combustion engines. It is extremely compact and has the great advantage of forming an integral part of the actual engine. The incorporation of this unit is simple and does not complicate the operation or maintenance of the engine. The rotating part of the unit is located on the crankshaft extension and supplies the necessary fly-wheel actior; there are no belts or vee drives, thereby excluding the possibility of failures by belts slipping and breaking.

The Dynastart Unit consists of an external bell-type armature, stator, automatic advance, contact breaker, ignition coil and condenser, voltage regulator, reverse current and solenoid switches. The magnetic system carries twelve poles of which six form the starter winding, whilst the other six carry the shunt winding. The current generated is utilised both for the high tension circuit through an ignition coil and also for lighting and battery charging. Starting is effected by push-button control, and during the starting cycle the Dynastart operates as a series motor. Driven by the engine the shunt winding is excited and generates current which increases with the engine speed. As.soon as the rated voltage of 12 volts has been reached the R.C. switch closes and charging of the battery begins. The standard voltage is maintained by automatic voltage control. The unit reaches its prescribed charging rate at speeds varying between 1200 and 1300 r.p.m. depending on the size. For output figures and technical information see table below.

The application of the Dynastart Unit is extended to the reversing of a two-stroke engine. This is achieved by changing the polarity of the field which is effected by the addition of a special solenoid switch.
This solenoid is assembled together with the Switch Assembly Box and the ignition Coil in the Switch Gear Box, which is illustrated above. its construction also ensures the separation of the contact breaker circuits for forward and reverse application. The Switch Gear Box has been introduced to provide a neat and compact assembly of the ancillary parts of the Dynastart Unit. All internal connections are wired to a Terminal Board which has been designed in a special pattern to facilitate the connection of the stators cable harness. The terminals of this cable harness form a matching pattern, thus eliminating the possibility of wrong connections. Although this Unit can only operate a two-stroke engine (without rotary valves) reversing is available for single as well as twin—cylinder engines.

The operation of the Siba Starter ignition switch is as follows:
(a) Forward. The switch is turned clockwise to the ignition “on" position which brings on the red warning light. Twisting the switch further in the same direction operates the starter. This second travel is spring loaded and the switch will, therefore, automatically return.
(b) Reversing. The switch must be brought back to the "off" position before depressing it, which will bring on the green warning light. The operations described above are then repeated providing in turn reverse ignition "on” and reverse starting. it should be noted that the design ofthe switch eliminates the possibility to move from the “forward" to the “reverse" without turning the ignition off.