Couplings with standard hub lengths
require fitting with keys through the full
hub length, and an interference fit on
shaft is necessary particularly when the
coupling is transmitting the maximum
rated power. Unless otherwise specified,
these hubs would be bored to give an
interference of between 0.0002 and
0.0007mm per millimetre of bore
diameter.
Couplings with extended hub lengths are
generally intended for use where
transition fits on shafts are preferred, and
unless otherwise specified, such couplings
would be bored to H7 tolerances. In these
instances axial restraint of the hub should
be provided by set screws.
Couplings transmitting the maximum
rated capacity, particularly where
relatively small shafts are being used,
often require 2 keys. This is more relevant
with larger sizes of couplings and, if in
doubt, full details should be supplied to
allow Bibby Transmissions’ engineers to
advise.
For all couplings, maximum bores are for
uniformly loaded drives only, using
rectangular parallel keys to
BS 4235 Part 1: 1972, or DIN 6885,
sheet 1, 1968. Taper and Square keys
should not be used with a hub boss
diameter to bore ratio of less than 1.5 : 1.
Bibbygear Series II Double Engagement
Gear Couplings are designed to
accommodate parallel and angular
misalignment and axial movement as
illustrated above.
Single engagement couplings
accommodate only angular misalignment
and axial movement.
Limited End Float couplings can also be
provided.
Whilst some sizes of Bibbygear Series II
Gear Couplings are capable of static
misalignment of up to 11/2° per gear mesh
it is recommended that all couplings be
aligned, on initial installation, to the
limits contained in the Installation and
Maintenance leaflet supplied with each
coupling.
Care should be taken to ensure that
misalignment during operation is kept to
an absolute minimum, as excesses will
cause wear of the product together with
high loading on associated machinery.
This will have a great influence on the life
of the product.