K E Y L E S S w o r k as the n a m e implies is a m e t h o d of winding the m a i n s p r i n g w i t h o u t the use of a key.
T h e r e are a few ways in which this is d o n e b u t we will consider the m e t h o d most used in wristwatches.
Figure 29 shows a typical a r r a n g e m e n t of keyless w o r k . T h e winding stem is t h r e a d e d at o n e e n d for t h e winding b u t t o n . At the base of the t h r e a d e d p o r t i o n is a shoulder t h a t w o r k s in the m o v e m e n t plate. B e n e a t h this shoulder a groove is c u t to receive the pin of the pull-out piece, a n d b e n e a t h the groove is a n o t h e r shoulder t h a t locates the c r o w n wheel. T h e r e m a i n i n g length is s q u a r e d to t a k e the castle wheel with t h e exception of the end which is t u r n e d d o w n to form a pivot.
T h e pull-out piece is retained in position by a shouldered screw. T h e c r o w n wheel r o t a t e s on the lower shoulder of the winding stem. T h e castle wheel h a s a s q u a r e hole a n d a l t h o u g h free t o slide u p a n d d o w n t h e squared p o r t i o n o f the winding stem m u s t nevertheless r o t a t e with it. T h e check-spring is held in position at o n e e n d by a screw, a n d the o t h e r end is positioned in the groove of the castle wheel. T h e u p p e r face of the castle wheel a n d t h e lower face of the crown wheel are cut w i t h identically s h a p e d ratchet teeth a n d are in mesh with each other. T h e u p p e r edge of the crown wheel is c u t with gear teeth which mesh with t h e transmission wheel. T h e b o t t o m face of the castle wheel is c u t with gear teeth a n d can be meshed with the intermediate wheel.
T h e n o r m a l position for this m e c h a n i s m is as shown in figure 29. T u r n i n g the winding b u t t o n a n d stem will cause the castle wheel to r o t a t e . Because the check-spring is holding the castle wheel in mesh with the c r o w n wheel t h e crown wheel m u s t r o t a t e as well.
In t u r n i n g the crown wheel, the transmission wheel on the t o p
p l a t e is r o t a t e d which, t h r o u g h the ratchet wheel, causes the m a i n s p r i n g t o b e w o u n d .
If a s h a r p pull is given to the w i n d i n g stem, the pull-out piece will t u r n with its screw causing the check-spring to be pressed d o w n w a r d . T h i s position is m a i n t a i n e d by the end of the pull-out piece d r o p p i n g into a step cut in t h e edge of the check-spring.
Fig. 29. Keyless work. 1. Winding button. 2. Winding stem. 3. Crown wheel. 4. Castle wheel. 5. Intermediate wheel. 6. Hour wheel. 7. Minute wheel. 8. Return bar. 9. Check spring. 10. Pull-out piece. 11. Pull-out
W A T C H A N D C L O C K R E P A I R S
Pressing t h e check-spring d o w n w a r d c a u s e s the castle wheel t o m o v e d o w n t h e winding stem, b e c o m e disengaged from t h e c r o w n wheel, a n d m e s h with t h e i n t e r m e d i a t e wheel which is in m e s h w i t h t h e m o t i o n w o r k .
In this position t u r n i n g t h e winding s t e m will o p e r a t e the m o t i o n w o r k a n d alter the h a n d setting.
A d o w n w a r d pressure on the winding b u t t o n will o v e r c o m e the resistance offered by the check-spring a n d the pull-out piece a n d t h e keyless w o r k will be restored to its original position.
If the winding m e c h a n i s m is stiff to o p e r a t e , inspect the ratchet wheel for freedom of m o v e m e n t . If the wheel is binding on the plate either the s h o u l d e r of the barrel a r b o r is n o t projecting clear of the plate or the a r b o r holes in the plate are w o r n .
In the first case, when screwing the ratchet wheel to the a r b o r t h e wheel will be pulled d o w n on to the p l a t e . Inspect the plate a n d the m a i n s p r i n g barrel for b u r r s a r o u n d the a r b o r hole a n d if necessary s k i m t h e surfaces in t h e t u r n s . T h e alternative is to fit a n e w a r b o r . If t h e a r b o r holes h a v e become enlarged the a r b o r will lean over causing t h e ratchet wheel to r u b against t h e plate. T h e remedy is to b u s h t h e a r b o r holes in t h e plate.
Slipping is caused by badly fitting wheels a n d badly meshed wheel teeth. T u r n the winding stem in the direction of winding a n d observe the effect on the wheels. If the c r o w n wheel slips on the castle wheel, the cause will be worn teeth or worn winding stem holes in the wheels or a w o r n winding stem. T h e wheels should n o t be loose on the stem. R e n e w a l of p a r t s will effect a c u r e .
If the u p - a n d - d o w n shake of the transmission wheel is excessive the action of r o t a t i n g the c r o w n wheel will cause the transmission wheel to be p u s h e d away, until the shake is t a k e n u p , resulting in insufficient d e p t h of mesh a n d subsequent slip. T h e transmission wheel s h a k e m u s t be reduced. First e n s u r e t h a t the transmission wheel boss is screwed d o w n tightly. If this is in order, then the height of t h e wheel bearing m u s t be reduced. S o m e transmission wheels a r e m a d e c o m p l e t e with a wheel b e a r i n g in the form of a boss. T h e length of this boss can be reduced by stoning. If the
bearing forms p a r t of the plate, then the height of the b e a r i n g m u s t be m a c h i n e d d o w n in the t u r n s .
Sometimes when pulling o u t the winding stem to alter the setting of the h a n d s , the stem c o m e s away from the m o v e m e n t . This is caused by the pin of the pull-out piece failing to retain the stem in position. If the pin of the pull-out piece, or the groove in
the winding stem are w o r n , replacement p a r t s will be required. If the winding stem becomes loose in the plate caused by t h e plate being w o r n , the excessive side-shake of the stem will result in partial disengagement of the pin of the pull-out piece in the winding stem groove. In such cases the plate m u s t be b u s h e d or an oversized winding stem fitted.
A n o t h e r cause of the winding stem c o m i n g away is the pull-out piece b e c o m i n g loose on the pull-out piece screw. W h e n correctly fitted the screw should be tight in the pull-out piece but free to m o v e in the plate so t h a t when the winding stem is pulled out or p u s h e d in, the pull-out piece a n d its screw rotate as o n e .
W A T C H A N D C L O C K R E P A I R S
W h e n the pull-out piece screw is in position m a k e sure t h a t the s h o u l d e r nearest the t h r e a d projects b e y o n d the face of the plate (Fig. 30, a). If it does n o t , it m e a n s t h a t when the pull-out piece screw is t h r e a d e d i n t o the pull-out piece, the pull-out piece will be held against the plate before the screw is fully tight (Fig. 30 b)