Is a Crank-Up Tower Forever? – Crank-Up Tower Safety & Inspections

A Crank-Up Tower is a handy way to be able to lower your antennas to protect them from extreme weather and for ease of servicing.

But the dark-side is that a Crank-Up Tower suffers from 100% cable dependency.

If the cables hold, the tower stays up.  If a failure happens the tower will drop in seconds, collapsing below the minimum height possible while rigged with cables.

Usually such a failure will write off the antennas, often the rotor and feed-lines and anything within the base of the tower is usually history.

Depending on the loading of the tower and side loads when it happens, the tower itself maybe damaged.

This danger is recognized by the “NO CLIMB” instructions and signage by Crank-Down tower manufacturers.  Even when at their lowest, a cable failure would drop the tower a few feet more, and the pinch points would seriously injure a climber or even knock them off the tower after hurting them.  As tempting as it may look, simply don’t do it – don’t ever climb a Crank-Up Tower.

Inspections go a long ways towards making sure your Crank-Up tower is as safe as it can be.

Inspection points include:

  • Cable Condition – no rust, no cut strands, no kinks, no unraveled sections
  • Cable Eyes and terminations (cable clamps are not recommended – the cables should be properly fitted with rigging grade swagged fittings at each end)
  • Limit Switch Function (if fitted)
  • Winch Condition
  • Cable Routing and securement
  • General Tower Condition, specially the pulleys & fittings for the Crank-Up portions.

If anything looks the least bit amiss, lower the tower to its lowest position if possible, and block the tower from further descent.  Several 4x4s rigged for each section might be a good solution for safety blocking.

Once blocked, make the needed repairs before raising the tower again.

If you cannot safely lower the tower, have a lift brought in and block it in the raised position before making repairs from the lift.

Here is what can happen if a cable breaks (click on the picture for a larger version):

What happens when a Crank-Up Tower breaks a Cable a all Sections Drop

 

 

Pretty sad picture. In this case a large 40m-10m Yagi suffered damage to a number of elements and a high-end rotor was destroyed.

On the plus side, no one was hurt and it looks like the tower survived in a repairable state. Cables and Micro-switches will need to be replaced, but the main structure looks ok on inspection.

In the pictured case a section of cable suffered rapid deterioration and an isolated portion of that one cable gave way.  Whether this was previously undiscovered lightening damage, some sort of galvanic reaction fallout or long-term cable decay missed in inspections, it isn’t certain.  The rest of the cable set looks like new, but without scheduled FULL visual inspections the damage area was not caught, instead causing the fall.

As part of your station plans, you should include periodic inspections of major safety items like Crank-Up Tower cables.  It should be right there with checking lightening protection gear, grounding, cable connector securement, antenna securement and all the other checks we need to make. 

I’m looking at doing my major checks twice a year.  A before-Winter major inspection and a mid-spring after-Winter major inspection.  I’ve selected these times knowing that the Wisconsin climate does 80% of its weather damage in 20% of the months, deep winter.

You may be better served selecting dates around your QTH’s weather extremes.

Additionally I will include re-inspection each time the tower is in a position to make an easy inspection.

On the tower selection side I am told that one time some of the Crank-Up Tower manufacturers offered dual-cable options as a built-in safety option, but have not found any currently being offered.

73

Steve
K9ZW

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6 thoughts on “Is a Crank-Up Tower Forever? – Crank-Up Tower Safety & Inspections

  1. […] replacement was lost when one of the support towers suddenly collapsed, as its crank-up cable perished from concealed […]

  2. […] My previous article on crank-up towers is at: Is a Crank-Up Tower Forever? – Crank-Up Tower Safety & Inspections  […]

  3. Marcelles sauners says:

    Hi,
    i am having sum problems with stinging my tower and the right hardware for ties.Think you can help? It will be appeciated.

  4. […] discussed the perils of Crank-Up tower safety for years – see:  https://k9zw.wordpress.com/2007/11/04/crank-up-tower-safety/ from late fall 2007 after I happened to be on the air in W9EVT’s hamshack when a tower cable […]

  5. Ric says:

    Perhaps “stop dogs” at each section would have saved this disaster. You would of course have to lock/unlock them from base, with a small cable run. These would relieve the constant strain/wear from the cable, as you set the dogs, then slightly slack the cable. Use a small drone to examine periodically.
    73, Ric, VE7CUP

    • k9zw says:

      Hi Ric VE7CUP

      Historically didn’t some crank-up towers include these safety catches?

      I know a few years back a local ham had one set up this way, but as both the lift cable and the safety cable were corroded he was offering the tower free to anyone who wanted to take it down. A small team carefully blocked each section of his tower, refitted the main cable while extended upwards, and then got it retracted & taken down.

      Another safety possibility is having more than one main cable, and again some of the manufacturers offered the option on select models.

      The only options I currently see is power retraction cables on some models of Tashjian Towers as well their cables upsized, then doubled up (dual cables), and again that positive pull-down cable being fitted.

      I didn’t spot these as upgrade options at others like, US Tower, but they may be available on request when ordered.

      One bad thing hams get into is never exercising their tower crank-up, not inspecting the cable(s), failing to lubricate the cable, use of low-grade & rust prone replacement cables and basically neglecting their tower for years on end.

      73

      Steve
      K9ZW

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