[TowerTalk] Brake Winches

[Patrick Greenlee]

As my on-order-but- not-delivered-yet new Tashjian tower has 2 each 1/2 
HP motors, one for extend and power retract and the other for tilt, I 
don't worry too much about manual cranking. I don't recall the gear 
reduction ratio but it was substantial, sufficient that I'd not want to 
have to crank it and crank it... manually.  No one mentioned anything 
about an option for cooling fans or cooling coils for the winches.  ;)  ;)

Patrick     NJ5G

On 6/29/2015 12:25 PM, Richard (Rick) Karlquist wrote:
>
>
> On 6/29/2015 8:53 AM, Patrick Greenlee wrote:
>> There is more than one type of winch brake.  Worm drives above a certain
>> reduction ratio won't "motor" or allow the load to turn the winch. There
>> are no brake parts as such but you get full control and if you turn lose
>> of the handle the load will not be able to turn the winch. No brake
>> parts = no brake parts to wear or overheat in use.
>>
>
> There is no free lunch with worm drives.  The worm drive IS a brake
> that is "ON" ALL the time, whether going up or down or standing still.
> As such, it causes at least a 2X increase in effort going up. Going
> down, the same friction applies so that you have to apply significant
> effort even with help from gravity.  All this extra effort due to
> friction HEATS up the worm gear.  If you replaced the worm drive with
> a recirculating ball bearing drive as used in vehicle steering, it
> would get rid of the friction and also get rid of the self braking.
> When you lower a tower, the gravitation energy has to go someplace,
> meaning it gets converted to heat.
>
> What is really needed is a braking system like they use for electric
> cars where the energy is fed back into the battery.  Probably not
> cost effective vs $150 winches.
>
> Rick N6RK