(fig. 4-54). Hydraulic fluid under pressure from the
cable-tensioner accumulator flows into the cable
tensioners, keeping tension on both sets of cables.
When one set of cables is loaded, the other set becomes
slack. Slack is taken out of the retraction-engine cables
by motion of the tensioners. An orifice in the supply
piping to each pair of cable tensioners allows limited
flow of fluid to the tensioners when the cables become
slack. When cable load is applied to the tensioner
piston, fluid flows back to the tensioner accumulator
through a check valve in parallel with the orifice in the
supply piping. When one pair of cable tensioners is
working, the stop nuts on the opposite tensioners
The clevis assembly is mounted on the end of the
tensioner piston rod (fig. 4-54). The clevis contains a
sheave that provides the means for transmitting the
force developed by the tensioner to the cable.
The sheave and adapter assembly mounted on the
carriage is used to guide the cables from the drum to
the tensioner sheave assembly. The sheave assembly
mounted on the tensioner frame guides the cables as
they pass from the sheave and adapter assembly to the
clevis assembly. The lead sheave assemblies guide the
cables between the retraction engine and the grab.
The cylinder assembly contains pressurized
hydraulic fluid from the tensioner accumulator, which
pushes the piston in the cylinder to move the piston rod
and clevis assembly. The movement of the clevis
assembly takes the slack out of the cables.
The drive system consists primarily of the advance
and retraction cables, lead sheaves, and the grab (fig.
4-55). This system provides the means for transferring
motion of the rotary retraction engine to the grab for
advance and retraction of the shuttle and piston
assemblies. Rotary motion of the retraction-engine
hydraulic motor is transferred to linear motion of the
grab by the drum and cables.
The sheaves are grooved wheels or pulleys that
guide and support the cables between the grab and the
rotary-retraction-engine drum. (See fig. 4-56,) The
sheave and adapter assembly mounted on the carriage
is used to guide the cables from the drum to the
Figure 4-54.Retraction-engine cable tensioners,