Zephyr ZGS-11000-2 v2 Operation And Maintenance Manual page 29

Manual RHGSE Operation and Maintenance Manual
Never continue operating with the cable wrapping tightly on the upper edge of the Spooler, as
the cable can come out of the Rotatub and twist and kink.
Technical notes
Effect of overall cable diameter
When a cable is new its diameter is at its maximum and is approximately .194 inches. As it is
accumulates time in service it wears and stretches and its diameter becomes smaller over time. As
the diameter is reduced the slippage on the capstans increases. As the slippage increases the tension
in the cable as it wraps on the Spooler increases. When this happens the cable may start to ride to the
top of the spooler. If this is noted during extending, the operator can slow down the Rotatub with a
hand or foot contact to allow the cable to fall to the bottom of the Rotatub in order to complete the
evolution. Afterwards the Rotatub clutch should be adjusted as per paragraph 7.15 above.
Effect of cable manufacturing process
When a cable is manufactured it is critical that the producer properly setup and engineer the
manufacturing process. During the manufacturing process the producer must strive to properly
balance the inner and the outer strands to create a spin resistant cable that will wrap on a modern
rescue hoist drum. In order to do this the wires and the strands are preformed so that they do not
abrade on each other under load and they do not tend to unwrap under load. If the preforming and
balancing is incorrect the cable will loosen up prematurely
Effect of cable lubrication
When a cable is new the internal spaces between the wires are full of the lubricant that is used
to draw them down to size. One rescue hoist manufacturer removes the external lubrication and the
other does not. Therefore it is the operator' responsibility to determine if adding additional lubricant is
required. If additional external lubricant is applied then the coefficient of friction is reduced and
slippage on the capstans increases.
Effect of worn capstans
The capstans will wear as a result of slipping and heavy loading. The first groove on the lower capstan
will wear out first because it has the heaviest load applied to it. The lower capstan is of a harder
material than the upper capstan. When the wear of the capstans becomes significant the cable will slip
excessively on the capstans. The results may be seen as the cable starting to ride to the top of the
spooler or twisting of the cable between the top of the RHGSE and the rescue hoist.
Zephyr International maintains excess inventory of spare capstans and has a trade in policy, whereby
when a user advises they need a new set of capstans, for a fixed price a new set can be sent out
immediately and the users then return the old pair to Zephyr for refurbishment.
In general in order to reduce cable slippage, reduce the cable load and or the speed of operation.
In a dusty environment the clutch should be disassembled and cleaned and lubricated with Mil-G-
81322 grease once a year.
Zephyr International llc Page 29 of 40
ZOM-11000-2 v2 rev E
United States Patent # 7,429,031 B1