Improvements in Expansion Gear for Bridges, Piers, and the like.
Year: 1898

page_text: Date of Application, 22nd Oct., 1898-Accepted, 26th Nov., 1898
COMPLETE SPECIFICATION.
Improvements in Expansion Gear for Bridges, Piers, and the like.
I, HARRY RIGBY, Civil Engineer, of Napier Yard, Millwall, in the County of
Middlesex, do hereby declare the nature of this invention, and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement:
-
This invention relates to expansion gear for bridges, piers and the like of the
class in which saddle plates are employed, one set being on the supporting masonry
and the other set on the under surfaces of the free ends of the girders of the
bridge or pier, and double ended knuckle blocks are fitted between the two sets
of saddle plates, the said knuckle blocks acting somewhat as a hinge thus allowing
for the lengthening or shortening of the girders under the influence of heat, cold
or from other causes.
It is however, possible, that if the lengthening or shortening of the girders
(due to expansion or contraction) is for any reason excessive or the piers or sup-
ports give way in any direction, the knuckle blocks may be inclined to such an
extent that they fall and slip sideways causing the girders to drop on to them
and necessitating the lifting of the entire bridge before the knuckle blocks can
be replaced. This invention has for its object to regulate the inclination of the
knuckle blocks so that when a certain angle has been reached further inclination
is not possible; and consists essentially in providing on the sides of the knuckle
blocks flanges or ribs either several in number or solid and extending for the
whole width of the knuckle block which when in the limiting position bear on the
saddle plates either at the top or bottom or both and prevent further inclination.
In order that this invention may be more readily understood, reference is had
to the accompanying sheet of illustrative drawings on which,
Fig. 1 is a diagrammatical view showing the application of this invention to
the girders of a bridge.
Fig. 2 is an end elevation showing a knuckle block in position.
Fig. 3 is a side elevation of the same.
Fig. 4 is a plan, the upper saddle plate being supposed removed.
Fig. 5 is an end elevation similar to Fig. 2 showing a slightly modified
arrangement.
Fig. 6 is a further modified arrangement.
Fig. 7 shows in perspective a knuckle block having solid ribs extending for
the whole of its width.
The saddle plate A is attached to the under surface of one of the bridge
girders C and the saddle plate B is mounted on the supporting masonry or other
support D. The saddle plates A B are constructed with rounded bearing sur-
faces a band with side bearing surfaces a¹ a¹, b¹ b¹. The knuckle block E is
double ended and its ends e e are adapted to fit on the bearing surfaces a b

page_text: respectively. The knuckle block E is further provided with side ribs or
flanges and as shown in Figs. 2, 3 and 4 the lower ends of these ribs or
flanges are adapted to bear on one of the bearing surfaces b₁₁ when the
knuckle block E is inclined to one side or the other.
When the girders C of the bridge expand under the influence of heat, they
ride on the knuckle blocks E and cause them to incline somewhat. When, how-
ever the knuckle blocks E are inclined to such an extent that the ribs or
flanges bear on the bearing surfaces 61, further inclination is prevented
although of course there may be still some lengthening of the girders. By this
means the knuckle blocks E are locked and prevented from slipping right over
out of place.
The limiting angle of inclination is adjusted according to circumstances so that
normally the knuckle blocks assume as near a vertical position as possible. It
will of course be understood that for contraction the action is similar but the
inclination is to the other side.
In the arrangement shown in Figs. 2, 3 and 4 the ribs or flanges e² e³ are
arranged equally on both sides so as to allow for both expansion and contraction.
In Fig. 5 the ribs or flanges e²e are shown adapted to bear on the bearing
surfaces a¹ a¹ of the saddle plate A instead of on the saddle plate B but the action
is identical with that described above.
Although the ribs or flanges e e³ are shown as equal on both sides, only one
may be provided on each side and these may be at opposite ends and facing in
opposite directions. As a result, one rib bears on one of the bearing surfaces b¹
while the other rib bears on one of the bearing surfaces a¹. By this arrangement
the angle of inclination is only limited in one direction.
Also the ribs or flanges may be as shown in Fig. 6, and adapted to bear on the
bearing surfaces a¹ a¹ on the top saddle plate A. and on the bearing surfaces 61 61
on the bottom saddle plate B.
The ribs or flanges &³may also extend for the whole width of the knuckle
block E as shown in perspective in Fig. 7.
The ribs or flanges e²e are preferably cast or otherwise formed in one with
the knuckle block and suitable strengthening ribs, clearance holes and the like
are provided in practice.
This invention is applicable for bridges, piers roof structures and girder work
generally and in all cases where provision has to be made for expansion and
contraction of the structure.
Having now particularly described and ascertained the nature of my said in-
vention, and in what manner the same is to be performed, I declare that what I
claim is:-
(1) In expansion gear for bridges, piers, and the like, the combination with
the saddle plate A, the saddle plate B and the double ended knuckle block E fitting
'between them, of ribs or flanges e e3 on the sides of the knuckle block E, the
said ribs or flanges e es being adapted to bear on the bearing surfaces a¹ a
or 61 6 and thus lock and limit the angle of inclination of the knuckle block E,
substantially as described with reference to Figs. 1 to 5 of the drawings and for
the purposes specified.
(2) In expansion gear for bridges, piers, and the like, the combination with
the saddle plate A, the saddle plate B and the double ended knuckle block E
fitting between them of ribs or Hanges e² 3 on the sides of the knuckle block E
the said ribs or flanges ee being adapted to bear on the bearing surfaces a¹ a¹
on the top saddle plate A and on the bearing surfaces 61 61 on the bottom saddle
plate B and thus lock and limit the angle of inclination of the knuckle block E,
substantially as described with reference to Fig. 6 of the accompanying drawings
and for the purposes specified.
(3) In expansion gear for bridges, piers and the like, the combination with

page_text: the saddle plate A, the saddle plate B and the double ended knuckle block E
fitting between them of solid ribs or flanges ³ ³ on the sides of the knuckle
block E, the said solid ribs or flanges e³ being adapted to bear on the bearing
surfaces a¹ a¹ or b¹ b¹ and thus lock and limit the angle of inclination of the knuckle
block E, substantially as described with reference to Fig. 7 of the drawings and
for the purposes specified.
D
1
1
00 1
1000
GEO. H. RAYNER,
37, Chancery Lane, London, Agent for the Applicant.