FOOTSTEPS.
341
pendant to absorb any play between the lower part of the gate section and
the sili.
Sluices.—Sluices for levelling the water on both sides of a pair of lock
gates preparatory to opening them^ may be fitted in the gates themselves,
alternatively to locating them in the side walls. The arrangement,
however, has the disadvantage of adding very considerably to the weight
of the gates, by reason of the apparatus required for opening and closing
the sluices. The question is discussed somewhat more fully in Chap. vi.
Platforms.—Gates are usually fitted with a gangway at or about coping
level. It is usually carried on brackets fixed to the topmost member of
the gate. The handrail or chain guard should be removable, in order to
facilitate the passing of warps and ropes
when the passage is open.
Anchorage. —The top of the heel-post,
or the upper pintle of a gate, revolves
in a horizontal collar, bolted to and
forming part of a suitable heavy casting,
known as the anchor block, from which
tie-rods or bars radiate to some distance,
their ends being bedded in massive
masonry. Several types of anchorage
are shown in figs. 281, 282, and 283.
Pootsteps. —The lower end of the
heel-post may either be arranged as a
pintle, fitting into a circular socket,
or it may be fitted with a hollow
------6"---------.
Sectional Elevation.
Fig. 285. —Gate Footstep.
casting to revolve upon a spherical surface. The latter arrangement is
illustrated in two forms in figs. 284 and 285. The first of these is more
suitable for small gates. In the second example, the play between the
cylindrical pivot and the sides of the lower casting, or cup, is designed
to allow of a slight clearance between the heel-post and the hollow quoin,
during the movement of the former, so as to diminish the friction. A