15
9. Adjustments & Maintenance - cont.
9. Adjustments & Maintenance - cont.
Fig. 9.9
Fig. 9.11
Replacing the Headstock Spindle Return Spring
The headstock spindle return spring is located on the opposite side of the
headstock to the rise and fall handle. It is pre-tensioned at the factory to the
correct tension and should need no adjustment through its life.
Warning: Unless the headstock spindle return spring is broken do
not attempt to remove it. The tension of the spring can cause the
spring cap to unwind with enough force to cause injury.
In the event that a broken spring needs replacing, remove the outer nut
from the threaded spindle then loosen the inner nut until the spring cap can
be pulled back to release it from the notch holding it in place,
Fig. 9.9
. To
release any remaining tension, turn the spring cap clockwise, taking care not
to let the cap spin as the broken spring may still be under a small amount
of tension. There is a loop on the side of the cap which can be held with the
thumb to give a better grip.
Once the cap is loose, remove the inner nut and take the cap and spring
from the threaded spindle.
Take the new cap and spring and place onto the threaded spindle,
Fig. 9.10
,
ensuring the central straight piece of the spring is inserted into the slot on
the threaded spindle,
Fig. 9.11
.
With the headstock spindle in its lowest position, carefully rotate the cap
anti-clockwise to apply tension to the spring. When enough tension has been
applied to retract the headstock spindle fully (to its highest position) secure
it onto the notch protruding from the headstock with the closest notch on
the cap and refit the inner nut to ensure the cap is fixed in place whilst also
allowing it to rotate freely as the spindle is raised and lowered. Refit the
outer nut and tighten to ensure the inner nut is secured in place,
Fig. 9.12
.
Use the rise and fall handle to pull down the spindle and test the tension
of the spring. If the spindle returns to its original position unaided then the
spring is at the correct tension. If not, more tension needs to be applied. If
the spindle returns with excessive force then the tension should be reduced.
Only enough tension need be applied to return the spindle gently to its
original position.
Fig. 9.12
Fig. 9.10
i
Kg
Threaded spindle
Spring
Notch