[TowerTalk] Crank up tower safety locks

[Jim Thomson]

UST already makes crank up towers with safety locks installed at the top of the 1st section only. 
They appear to be made of 1 inch thick plates, two such plates used at each corner.   A pull rod
runs down the side of the tower to grnd level.   Short rods are installed between the 3 x corners
at the top of the 1st section.  When the pull rod is pulled down, the 3 plates swivel and lock the
tower into place.   This feature can be used at any height  from  fully nested to fully extended.

However they can’t be engaged just willy nilly.  The tower has to be in specific locations so cross bracing
is not in the way of the safety lock plates.   The upper sections do not require the safety locking plates, since the
upper sections all use one steel raising  cable PER FACE !!   IE:  3 x lift cables for EACH of the upper sections.

The only way the upper sections can collapse is for all 3 x lift cables on any given section to break simultaneously. 
While the tower is being raised or lowered, the  single lift cable  from the winch drum is holding the entire tower up.
IF it broke while  raising or lowering, the tower will collapse.   However, once the tower is raised to  XXX height, and 
safety plates are engaged, the  load is then taken off of the main lift cable on the drum.    At that point the upper sections
can be guyed in most cases, since the upper sections have 3 x lift cables per section. 

You have to be careful you don’t leave a ton of slack in the primary lift cable in any of these safety plate schemes. Too
much slack, and the lift cable could jump the pulley. 

My own HDX-689  does not have the safety lock feature.   However, the upper sections do have 3 x cables per section 
( except for the very top section, which only has 1 lift cable. ) .  To make it safe foe climbing, a steel section of
2 inch tall x 6 inch  wide  x  .25 inch  thick rectangular steel tubing can be inserted  just below the bottom of the 2nd section.
Some have also used 4 x4  or 6 x 6 wooden posts for this application.   Up to 3 can be used. 

Jim   VE7RF