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The Watt Type Governor

The Watt type Governor was widely used in early beam engines. It works by using centrifugal force from rotating weights to control the position of a throttle valve based on engine speed. As engine speed increases, the weights fly further outwards and upwards, closing the throttle valve to reduce steam flow and maintain a steady speed. This simple governor provided basic speed control suitable for agricultural and pumping applications where high precision was not essential.

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Umair Ashraf
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152 views4 pages

The Watt Type Governor

The Watt type Governor was widely used in early beam engines. It works by using centrifugal force from rotating weights to control the position of a throttle valve based on engine speed. As engine speed increases, the weights fly further outwards and upwards, closing the throttle valve to reduce steam flow and maintain a steady speed. This simple governor provided basic speed control suitable for agricultural and pumping applications where high precision was not essential.

Uploaded by

Umair Ashraf
Copyright
© Attribution Non-Commercial (BY-NC)
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOCX, PDF, TXT or read online on Scribd
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The Watt type Governor

Probably the most widely used governor in the early days, it is named the Watt governor
because James Watt applied it to his early beam engines. He did not however invent it
as it had been in use on wind and water mills many years before this.

A belt or gearing from the engine crankshaft drives the input shaft 'm' causing the bevel
gears 'l' to revolve and in turn rotate the vertical shaft 'a'. The bracket 'b' at the top of 'a'
supports two arms 'c' which are pivoted at the top, at the end of the arms are two very
heavy metal weights 'B' partway along the arms 'c' are fixed two pivoted link arms 'd'
which link to a collar 'c' which rotates with them but is able to slide up and down shaft 'a'
.

The up and down motion of this collar is followed by a pair of pins 'f' which move a bell
crank 'g' which is in turn linked to a throttle actuating rod 'i' linked to a throttle or butterfly
valve in the supply of steam to the engines cylinder which can allow more or less steam
through.

At rest the governor weights are held in the lowest position by gravity, the throttle will be
in its most open position. As the engine speed increases these weights rotate faster
until centrifugal force exceeds that of gravity and they fly further outwards and as a
result of the linkages, upwards, this movement is transmitted to the trottle valve which
begins to close. The faster the governor is driven the further out the weights move and
the more the throttle is closed, until the amount of steam it lets through balances the
demand and the engine speed stabilises.

If the load the engine drives is reduced it will increase speed, the governor restricts
steam flow more until the speed stabilises, if load is added to the engine the speed
drops, the throttle is opened more and more steam allowed in to compensate for the
demand.

The Watt governor is a simple governor but is not terribly accurate where very fine
control of speeds in needed and so was superceeded in many applications by more
specialised and accurate governors, however for many agricultural end pumping
engines where absolute speed was not essential it survived and can still be seen on
numerous preserved engines.

Expansion Governors
A similar effect but with a much more rapid response (although lower levels of
efficiency) resulted when the expansion slide valve was driven either from an eccentric
where governor movement varied the throw of the eccentric (and thereby altered the
range of movement on the expansion valve as
above) see also the .

 
 

Or as with the Hartnell expansion governor above, from a fixed eccentric via an
expansion link (l) and die block (h), the position of which is governor controlled and
either increases or decreases the travel of the expansion valve rod (k), admitting steam
earlier or cutting it off earlier depending on speed or load (see also the description of the
expansion governor)

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