Improvements in the Construction of Temporary Bridges and other like Structures.
Year: 1892

page_text: Date of Application, 31st May, 1892
Complete Specification Left, 28th Feb., 1893-Accepted, 22nd Apr., 1893
PROVISIONAL SPECIFICATION.
Improvements in the Construction of Temporary Bridges and other
like Structures.
I, FRANCIS WELDON, of Erlimount, Earley, in the County of Berks., Colonel in
the Indian Staff Corps, do hereby declare the nature of this invention to be as
follows:-
My invention relates mainly to the construction of a "trestle-transom," for use
in the formation of temporary bridges of the class described in the Specification
of the Letters Patent granted to me, bearing date 29th July 1890, and
numbered 11,882, but the use of my invention is not necessarily confined to this
particular form of structure.
The object of the invention is the construction of a device, which will attach a
cross-beam to upright posts in an absolutely rigid manner, while at the same time
it permits the said cross-beam to be raised or lowered and adjusted to any required
position on the posts, with great facility.
The said device is constructed substantially as follows.
The ends of the cross-beam abut against the inner sides of the posts, and are
held thereto by a rectangular metal frame, which may conveniently be formed of
two flat bars, united by a bolt at each end.
One of the said bolts passes through a hole bored horizontally through the
crossbeam near the end and below the centre, while the other bears against the
outer side of the post, the post being within the frame. The side bars of the frame
are of such a length, or the hole in the cross-beam is bored in such a position, that
the bolt bearing against the post is just below the level of the top of the beam, the
sides of the frame being at a slight angle. The parts being in this position the
cross-beam will be rigidly held to the posts, and the greater the weight upon
the beam, the more tightly will the attachment grip the posts.
A considerable amount of friction is set up between the ends of the beam and the
posts, which to a great extent assists in the rigidity of the structure.
To release the beam, it is only necessary to loosen the bolt and deliver a blow or
blows on the outer ends of the frames, which then immediately become loose and
enable the bean to be raised or lowered. To fix it in position, a check is applied
to the outer ends of the frames, when the weight of the beam at once automatically
locks the structure again together.
AMBROSE MYALL,
21, Cockspur Street, London, S. W., Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Construction of Temporary Bridges and other
like Structures.
I, FRANCIS WELDON, of Erlimount, Earley, in the County of Berks., Colonel in
the Indian Staff Corps, 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 :-
My invention relates mainly to the construction of a " trestle-transom," for use in
the formation of temporary bridges, of the class described in the Specification
of the Letters Patent, granted to me bearing date 29th July 1890, and
numbered 11,882, but the use of my invention is not necessarily confined to this
particular form of structure.

page_text: The object of the invention is the construction of a device which will attach a
crossbeam to upright posts in an absolutely rigid manner, while at the same time it
permits the said crossbeam to be raised or lowered and adjusted to any required
position on the uprights with great facility.
In the accompanying three sheets of drawings, which form part of this
Specification;
Fig. 1. is an elevation of one end of a crossbeam and a post connected by means
of my improved device.
Fig. 2 is a similar view shewing the device loosened and the crossbeam ready for
raising or lowering.
Fig. 3. is a plan of the said device.
"of a temporary bridge, with the
Fig. 4. is an elevation of a "trestle-transom
parts attached in accordance with my invention.
Fig. 5. is a plan of one of the attaching devices.
Fig. 6. is an elevation, of one end of the said "trestle-transom " shewing the
improved attaching device in a different position.
Fig. 7. is a similar elevation shewing the devices loosened and the method of
raising or lowering the crossbeam.
Similar letters of reference denote similar parts throughout the drawings.
Referring first to Figs. 1, 2 and 3, B is an upright and F a crossbeam. The end
of the said crossbeam abuts against the upright and is held thereto by means of my
improved device, hereinafter called "the grip strap," consisting of a rectangular
metal frame, which may conveniently be formed of two flat bars A A, united at the
ends by bolts C and C¹.
The bolt C passes through hole bored horizontally through the crossbeam F
near the end and' below the centre, as shewn, while the other bolt C' bears against
the outer side of the upright B, the said upright being within the rectangular frame
and embraced thereby. The side bars A. A of the said frame are of such a length,
or the hole in the crossbeam is bored in such a position that the bolt C¹ bearing
against the upright B, is a little below the level of the top of the beam F, the side
bars A A forming a slight angle above the lower side of the crossbeam, as shewn
in Fig. 1. It is to be assumed that the other end of the beam F, not shewn in the
figure, is similarly attached to another upright. The parts being in the position
above described, the crossbeam will be rigidly held to the uprights and the greater
the weight upon the beam the more tightly will the device grip the uprights. A
considerable amount of friction is set up between the ends of the beam and the
uprights, which to a great extent, assists in the rigidity of the structure.
To release the beam F it is only necessary to loosen the nut of the bolt C¹ and
deliver a blow or blows downwards on the outer ends of the straps, which then
immediately become loose, as shewn in Fig. 3 and enable the beam to be raised or
lowered.
To fix it in position a check is applied to the outer ends of the straps, when
the beam being allowed to. descend, its weight at once automatically locks the
structure together again.
To further ensure the rigidity of the structure and also to aid in supporting the
crossbeam, I sometimes combine with the grip strap one of the devices described
and shewn in the Specification of my aforesaid Letters Patent No. 11882 of 1890.
Such combination is shewn in Figs. 4, 5, 6 and 7, F is the crossbeam, B B the
uprights and A. A the grip straps, as before described.
Q is the platform of the bridge resting upon joists Q' carried by the crossbeams,
but such platform may be arranged in any other suitable manner. The additional
device hereinafter called "the lever strap" and described in my aforesaid Specifi-
cation, consists of flat bars J J', united by four bolts K K' and L L'. The bolt L
bears against the upper side and the bolt L' against the lower side of the cross-
beam F, the bolt K against the outer side of the upright B and the bolt K' against
the wedge M driven between it and the inner side of the upright. The lever strap
should preferably form with the crossbeam an angle not greater than 45° when the

page_text: bolt bears against it. When the wedge M is driven down the lever strap braces
the structure and assists in supporting the crossbeam owing to its lever grip of the
upright caused by driving in the said wedge.
The normal position of the parts is shown in Fig. 4, and the outer joist at each
side is preferably placed, as shewn, between the bolt L' and the upright B, thereby
evenly distributing the platform load over the whole length of the crossbeam and
relieving the span between the two bolts L L' of a portion of the weight.
If the outer end of the grip strap A be driven downwards so that it embraces
the upright B below the crossbeam, as shewn in Fig. 6 and the bolts be fairly
tightened to preserve their positions, the said crossbeam becomes absolutely immove-
able and the whole trestle can be freely handled and moved about as one piece,
without any possibility of the relative positions of the said crossbeam and uprights
being altered.
When it is desired to raise or lower the crossbeam, a bracket R, Fig. 7 is attached
to the upright, and the said crossbeam connected thereto by a differential pulley S,
the grip strap is now loosened, as previously described with reference to Fig. 2, and
the wedge M being knocked out the crossbeam is perfectly free of the upright and
can be readily raised or lowered by one man.
As the bracket R overhangs the end of the crossbeam to which the lower block
is attached, the strain of the pulley tends to force the upright away from the end
of the crossbeam and thus friction is avoided during the process of adjustment.
Any other arrangement of pulleys may be employed, but the differential is found
most convenient in practice.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be perforined, I declare that what I
claim, is:-
1. The attachment of a crossbeam to an upright by a gripping device, consisting
of a rectangular frame, one of its short members passing through said crossbeam
below the centre, the other short member bearing against the outer side of said
upright, below the top of said crossbeam, said upright being embraced within said
frame and the long members of said frame being at a small angle with said cross-
beam, the grip increasing as the load on said crossbeam is increased, while said grip
is released by a downward blow on the outer end of said device, substantially as
described.
2. The attachment of a crossbeam F to an upright B by a gripping device, con-
sisting of two bars A A united by bolts C C¹, the bolt C passing through said
crossbeam below the centre, the bolt C¹ bearing against the outer side of said
upright below the top of said crossbeam, said upright being embraced within
said device and said bars A A being at a small angle with said crossbeam, the grip
increasing as the load on said crossbeam is increased, while said grip is relieved by
a downward blow on the outer ends of said bars A A, substantially as described.
3. In the construction of a trestle-transom, or other similar structure, the attach-
ment of a crossbeam F to uprights B B by gripping devices consisting of bars A A
united by bolts CC', the bolts C passing through said crossbeam below the centre,
the bolts C' bearing against the outer sides of said uprights below the top of said
crossheam, said uprights being embraced within said devices and said bars A A
being at a small angle with said crossbeam, in combination with devices consisting
of bars J J united by bolts K K and LL' the bolts L bearing against upper side
and the bolts L' against the lower side of said crossbeam, the bolts K bearing
against the outer sides of said uprights and the bolts K' against wedges M driven
between them and the inner sides of said uprights, substantially as and for the
purpose described.
ليوم
1
1000
AMBROSE MYALL,
21, Cockspur Street, London, S.W., Agent for the Applicant.