Pulleys And Counting Pulleys - C-Max CM2 User Manual

CM2 Sidescan Sonar User Manual

19. Pulleys and Counting Pulleys

19. PULLEYS AND COUNTING PULLEYS
Pulley Types
There are two sizes of the pulley designed for use with CM2 tow cables. These are snatch-block types; the
pulley does not need to be disassembled to fit or remove the cable. There are also two versions of the
smaller sized pulley. The three types are Type O, the original pulley. Type S ("small") has the same diameter
wheel but has a later style of frame. Type L ("large") has a wheel that is twice the diameter but also has the
later style of frame.
Type O and S are suitable for use with "soft" polyamide-reinforced cables up to 8mm diameter and with
steel-armoured cables up to 6.4mm diameter.
Type L is suitable for use with "soft" polyamide-reinforced cables and with steel-armoured cables up to
11.5mm diameter.
All types may be used as simple pulleys or, with addition of a Pulley Sensor and cable, are suitable for
conversion to counting pulleys.
Counting Pulley, Type L
Cable Guides
If a pulley is to be used with a polyurethane-sheathed tow cable there may be circumstances where the
"stickiness" of the cable would cause it to ride up on the rim of the pulley and jam where it reaches the
supporting arms. This is more likely when the cable is only under light tension, insufficient to pull the pulley
into line with its path. This "riding up" is unlikely to occur with a steel-armoured cable in normal use.
To avoid the problem of PU cables riding up, an optional cable guide set is available for fitting to Type L
pulleys. These guides are raised for loading the cable, then dropped into position over the pulley rim to guide
the cable and ensure that it cannot ride up.
Version 3.6 (2008)
41