[Milsurplus] Does anybody remember a torque amplifier?

[Bruce Gentry]

Bruce Gentry wrote:
> Jim Haynes wrote:
>> I have a mental image from 50+ years ago of a thing painted OD and
>> having a motor on it, and an input shaft and an output shaft.  It was
>> called a torque amplifier.  The power was supplied by the motor and
>> a little bit of effort to turn the input shaft resulted in the output
>> shaft turning the same amount with a lot more torque.  I guess it had
>> been used in something like a radar-controlled gun aimer, or maybe
>> just a manually controlled gun aimer, to allow some low-power control
>> input to maneuver the output that required a lot more power.  I'm
>> not at all clear on how the thing worked.
>>
>> I recently googled for "torque amplifier" but it seems that some
>> tractor manufacturer applied that term to a low gear so most of
>> the hits are about tractors and repairing same.
>>
>> The context of the question is an item on slashdot in the past week
>> concering a guy who has invented a transmission that is infinitely
>> variable from reverse to a high forward speed and says that all power
>> transmission is through gear teeth - no belts or clutches.  So I'm
>> wondering if he has just re-invented the WW-II era torque amplifier,
>> or maybe invented a new way of making one.
>>
>> Or am I just imagining the whole thing?
>>
>>
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>>   
> I have seen and experimented with one of these. It works like power 
> steering on a vehicle, but can be turned as many turns as desired in 
> either direction. It would indeed be a great help in training a gun. 
> They work in one of two ways, hydraulic pump and motor or friction 
> discs.  An input causes  a difference to be observed between the input 
> and output, which engages the drive and causes the output shaft to 
> follow the motion of the input precisely, but with much greater 
> force.   A mechanical servo and a fine example of the quickly 
> disappearing art of mechanical engineering.  Bruce Gentry
>