& Derrick span gear (topping lift) winches
8.1. Driven by adjacent winch'
8.1.1. (1) A derrick span gear winch driven by a rope whip
from an adjacent power-driven winch should have two separate
drums, one for the rope whip and the other for the derrick span rope,
or a single drum divided into two parts by a substantial flange of
sufficient depth to ensure effective separation of the ropes.
The winch should be fitted with sprockets on each side of the
drum or part of the drum containing the span rope, as well as with
pawls cross-connected in such a manner that they engage into the
The sprockets should be of such a shape that the pawls tend
to engage harder when under load.
The pawl-operating gear should be fitted with suitable hand-
holds to enable the pawis to be engaged or disengaged safely.
The pawls and sprockets should be designed to be capable of
resisting a torque not less than 1 5 times the maximum torque
induced by the derrick when it is in conditions of maximum resultant
force. The winch should bear a plate in a conspicuous position
containing the following information:
the direction of rotation of the drum when the derrick is being
the size of wire rope for which it has been designed;
the working length of wire rope it has been designed to accom-
particulars of its identity; and
a warning notice to the effect that the derrick must not be topped
or raised while it is bearing a load.
1See also paragraphs 4.2.1(a), (c), (d), 4.7.4, and 4.8.1, which are applicable.