(a) Not be used for heavier strains or lines than those
for which they are constructed;
(b) Be fitted with line guards;
(c) Be designed and used to prevent fouling;
(d) Be kept in proper alignment when in use;
(e) Be equipped with bearing and yoke pins that will
safely withstand the strains imposed, and are securely
fastened; and
(f) Be equipped with sheaves designed for the size of the
wire rope used.
EXCEPTION:
Subsections (b), and (f) do not apply to rig-up ("Tommy Moore") blocks.
(2) Blocks with cracked or excessively worn sheaves or
shells must not be used.
(3) Block bearings must be kept well lubricated.
(4) All pins in blocks must be properly secured by "Molle
Hogans" or keys of the largest size the pin hole will
accommodate. When blocks are hung in spars, pins must be
secured with a nut and cotter pin or nut and molle.
(5) Lead blocks used for yarding, swinging, loading and
unloading used in wood spars shall:
(a) Be of the type and construction designed for this
purpose;
(b) Be bolted with not less than two bolts through the
shells below the sheaves in a manner that will retain the
sheave and line in case of bearing pin failure (this does not
apply to haulback lead blocks); and
(c) Mainline blocks shall have a sheave diameter of not
less than twenty times the diameter of the mainline.