IMPROVEMENTS IN SPRING BALANCES
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by Robert Lamont at the Office of the
Commissioners of Patents on the 16th December 1881.
"
ROBERT LAMONT, of Kilmarnock, in the County of Ayr, North Britain.
IMPROVEMENTS IN SPRING BALANCES."
This Invention has for its object to improve the construction and action of spring
balances, and more especially to reduce the amount of the oscillating or vibrating
action which occurs when ordinary spring balances are used.
In carrying out the Invention one, two, or more helical springs are employed,
and with such spring or springs there is combined apparatus contrived so that
when an elongation of the spring or springs takes place in consequence of the
application of an article to be weighed, a fluid has to pass through one or more
small holes or passages, and the forces tending to produce oscillation or vibration are
spent in moving the fluid. The action on the fluid takes place only whilst the
length of the spring or springs is being changed by the action of the applied weight,
and it does not appreciably alter the position finally assumed by the parts nor the
indication of weight thereby obtained. The apparatus for thus checking vibration
may be arranged in a variety of ways.
In one modification a pair of springs have their movable ends connected to a
cross bar which has a cylinder fixed to it containing the fluid, which fluid for many
purposes may advantageously be glycerine. In the cylinder there is a piston or disk
the rod of which is fixed to the same piece as the fixed ends of the springs, and this
piston or disk is made with holes through it or with a corrugated edge or it is
made so much smaller than the cylinder as to allow the fluid to pass in a suitable
manner. When the springs are drawn down by a weight, the cylinder descends
with them, but only at the rate at which the fluid can pass from the upper to the
underside of the piston, and extremely little or no vibration or oscillation takes
place before the parts settle in the position corresponding to the weight of the
article hung on the balance.
Amongst the various modifications of which the apparatus is susceptible the
following may be instanced. A single spring may be used with the cylinder fixed
to the bottom of it and the piston rod passing up through the spring. The spring
may be inside the cylinder and the piston or disk either inside of the spring or at
D

page_text: its upper end, or fixed to the middle part of the spring. The cylinder and piston
may be inside of the spring. There may be one or more stationary cylinders with
one or more springs having their movable end or ends connected to the piston or
pistons. In some cases and particularly if the spring is made of a flat or other
suitable form and placed in the fluid the piston may be dispensed with, vibration
or oscillation being checked in consequence of the parts of the spring having to
move through the fluid. The parts may be arranged either for suspending the
articles to be weighed or for having the articles placed above the springs as in table
or platform balances.
The cylinder may be made with an open top or with a more or less confined
passage for the piston rod. There may be a tube for the piston rod to pass through,
and if this tube descends into the cylinder and the upper part of the cylinder is
enlarged the apparatus will be capable of being inverted without spilling a liquid
contained in it. The cylinder may be arranged to rise up to a lid or stopper when
there is no weight on the balance; or it may be closed with a flexible or elastic
cover attached to it and to the piston rod but allowing of the necessary relative
motion.
The quickness of action may be rendered adjustable in various ways; an
adjustable valve may be provided for covering more or less of the holes through the
piston, or the piston may be hinged to the rod with provision for adjusting it more
or less obliquely. The top and bottom of the cylinder may be connected by a
lateral passage fitted with an adjustable valve.
The cylinder or an equivalent vessel may be fitted with a flexible diaphragm
instead of the piston, there being a suitable passage through the diaphragm or
otherwise from one part of the vessel to the other. Or the diaphragm may be rigid
and the two parts of the vessel flexible or formed with flexible sides.