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Useful And/Or Interesting Data
(More will be added from time to time)
is a unit used to express the power (rate of doing work)
of an engine in the
imperial system of measurements. The
term horsepower was first used
by the Scottish engineer James Watt. He used it to compare the power of steam engines to the power
The term was later used
to express the power of such devices as car engines, jet engines, electric
motors, and nuclear reactors.
horsepower is defined as 550 foot-pounds of work per second, or 33,000
foot-pounds of work per minute.
foot-pound is the work needed to lift one pound one foot.
The metric unit of power is the watt.
horsepower equals 745.7 watts
an engine lifts a 550-pound object to a height of 2 feet in 1 second,
working at a rate of 1,100 foot-pounds per second (550 X 2 divided by 1 = 1,100).
This engine is delivering 2 horsepower (1,100 divided by 550 = 2).
If a 150-pound man climbs
to a height of 88 feet, he does 13,200
foot-pounds of work (150 X 88 = 13,200). If
the man makes this
climb in 1 minute (60 seconds), he is working at a rate of
4/10 horsepower (13,200 divided by 60 = 220; 220 divided by 550 = 4/10).
A person who is accustomed to hard work can work at a rate between 1/10
and 1/8 horsepower continuously during an 8-hour day.
power of an engine was measured in indicated horsepower, or brake horsepower.
It is now usually measured in watts.
is a measurement of the power produced inside the cylinders of an engine.
The power in foot-pounds per minute is first calculated by multiplying
together the average pressure on the pistons,
the area of each piston, the
length of the piston's stroke, the number of power strokes per minute,
number of cylinders in the engine. This
power must be divided by 33,000 to
give the engine's indicated horsepower.
is sometimes called effective horsepower, because it is the amount of power
available at the engine's shaft.
horsepower is measured by a dynamometer. This
instrument measures the engine's speed and the torque
(amount of twist) exerted
by its shaft. It is lower than
indicated horsepower because friction in the
engine wastes part of the power
produced in the cylinders.
There are many different types and sizes of
threads. Listed here are a few you may have heard of.
Nowadays the most common threads are
metric. When our stationary engines were
made the old British threads were used. Without doubt the most useful
spanner I have in my toolbox is a very old 1/2" AF (Across Flats).
||British Standard Whitworth - This was
the first standardised thread form. Sir
Joseph Whitworth proposed this thread in 1841.
||British Standard Fine - Since 1908
this thread, in conjunction with BSW has been the mainstay of British
Engineering, and was used when finer pitches were required.
||British Standard Brass - Because brass
tubing has a uniform wall thickness, irrespective of the tube diameter,
any thread cut on it, would have to have the same depth, so 26 tpi
is standard on all diameters.
||British Association - In the 1890's,
the British Association for Advancement of Science (BA) realised there
were no English screw thread standards for small electrical and
scientific equipment, so they proposed the BA system loosely based on
the Thury threads already in use in Europe (hence the metric sizes).
||Unified Course - This thread was
standardised in 1918.
||Unified Fine- This thread was also
standardised in 1918.
||Unified Extra Fine - This thread
was used for special purposes.
||ISO screw threads are the world-wide
most commonly used type of general-purpose thread. They were one of the
first international standards agreed when the International Organisation
For Standardisation was set up in 1947.
12 volt Regulator Details
drive a 12 volt car dynamo from my Lister D, which in turn supplies the
electricity for the lighting display board.
In order to control the voltage output from the dynamo a regulator is
required. I have seen many car dynamos being driven
engines on the rally field, and so I thought it may be useful to include some
details here. The following details are for
the very familiar Lucas type voltage regulator. Note that we are talking about the old fashioned DC dynamo, not the more modern
Obviously the first picture here is shown with the black
regulator cover removed.
If you click on the pictures on the left you will see
a better sized image.
The car voltage regulator consists of two parts - the "voltage
regulator" (the left coil) and the "cut-out" (the right
Lets deal with the cut-out first. This acts like a switch which
operates at a given dynamo output voltage. When it switches in, as
the dynamo speed increases, it
connects the car battery to the dynamo via the regulator, and hence
charging can commence. When the output voltage is too low (at low
dynamo speeds) the cut-out drops out to prevent the battery trying to run
the dynamo like a motor, which would quickly drain the battery. From
this you can see that the cut-out is of no use to us if we are just using
the dynamo to run some lights from our stationary engine. I've
included it's explanation for interest, as it's an integral part of the
whole regulator box.
||The part that we are
interested in is the left hand coil, the regulator.
This is the part that controls the maximum output voltage from the
spinning dynamo. It's important that we control this voltage
otherwise any lights we connect could quickly fail. You can see from
the detailed view on the left that the adjustment screw is number 2.
(Important! Note that it is shown as screw number 1 in the overall view
above). Using a volt meter connected to the output terminals to the
lights, adjust the screw with the engine and dynamo running at normal
speed.. I tend to run my dynamo at about 10 volts which helps to
extend the lamp life, although it does reduce the light intensity a
Looking at the above will give you an idea of how it works. Below
you will find out how to actually connect the parts together.
|A1 A F D E
A1 Connect this terminal to the positive (+) side of the lights,
ideally through a fuse. If you are using several lights then a good
sized cable should be used.
A This terminal is left blank. (It would normally be
connected to the car battery. positive (+) terminal).
F Connect this terminal to the field winding on the
dynamo. This is the small terminal on the back of the dynamo.
D Connect this terminal to the large one on the rear of the
dynamo. This cable takes all the load and so use good sized wiring.
E This is the earth terminal. Connect this to the main
body (metal casing) of the dynamo using good sized wiring again.
Also connect this terminal to the negative (-) side of the lights
An old 12volt car dynamo looks pretty harmless, but it is capable of
generating quite a few amps.
It is therefore important to ensure all your connections are tight and the
proper sized cable is used in order to avoid overheating and damage.
I have tried to make the above as clear as
possible. If you need any more details just ask.
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