Pump Primer 1 $100 - 8 Hours - Technical Learning College

Dudley Castle Engine
The first engine may have been erected in
Cornwall in 1710, but the Dudley Castle
engine of 1712 is much better known and
thoroughly documented. The first pumps
used in Cornwall were called bucket pumps,
which we recognize as lift pumps, with the
pistons somewhat miscalled buckets. They
pumped on the up-stroke, when a clack in
the bottom of the pipe opened and allowed
water to enter beneath the piston. At the
same time, the piston lifted the column of
water above it, which could be of any
length. The piston could only "suck" water
33 ft, or 28 ft more practically, of course, but
this occurred at the bottom of the shaft, so
this was only a limit on the piston stroke. On
the down stroke, a clack in the bucket
opened, allowing it to sink through the water to the bottom, where it would be ready to make
another lift. More satisfactory were the plunger pumps, also placed at the bottom of the shaft. A
plunger displaced volume in a chamber, forcing the water in it through a check valve up the
shaft, when it descended. When it rose, water entered the pump chamber through a clack, as in
the bucket pump.
Only the top of the plunger had to be packed; it was not necessary that it fit the cylinder
accurately. In this case, the engine at the surface lifted the heavy pump rods on the up-stroke.
When the atmospheric engine piston returned, the heavy timber pump rods did the actual
pumping, borne down by their weight. A special application for pumps is to produce a vacuum
by exhausting a container, called the receiver.
Hawksbee's Dual Cylinder Pump
Hawksbee's dual cylinder pump, designed in the 18th century, is the final form of the air pump
invented by Guericke by 1654. A good pump could probably reach about 5-10 mmHg, the limit
set by the valves. The cooperation of the cylinders made the pump much easier to work when
the pressure was low. In the diagram, piston A is descending, helped by the partial vacuum
remaining below it, while piston B is rising, filling with the low-pressure air from the receiver.
Bell-jar Receiver
The bell-jar receiver, invented by Huygens, is shown; previously, a cumbersome globe was the
usual receiver. Tate's air pump is a 19th century pump that would be used for simple vacuum
demonstrations and for utility purposes in the lab. It has no valves on the low-pressure side, just
exhaust valves V, V', so it could probably reach about 1 mmHg. It is operated by pushing and
pulling the handle H. At the present day, motor-driven rotary-seal pumps sealed by running in oil
are used for the same purpose. At the right is Sprengel's pump, with the valves replaced by
drops of mercury.
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