US3010128A

US3010128A - Mobile self propelled bridge units

Info

Publication number: US3010128A
Application number: US666262A
Authority: US
Inventors: Gillois Jean; Gehlen Hermann Walter
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-06-04
Filing date: 1957-06-03
Publication date: 1961-11-28
Anticipated expiration: 1978-11-28

Description

1951 J. GILLOIS ET AL MOBILE SELF PROPEILLED BRIDGE UNITS 8 Sheets-Sheet 1 Filed June 3, 1957 INVENTOPS Jean GILLO/S Hermann Walter GEHLEN Nov. 28, 1961 J. GILLOIS ETAL 3,010,128

MOBILE SELF PROPELLED BRIDGE UNITS Filed June 3, 1957 8 Sheets-Sheet 2 INVENTOR-S "I l Jean G/LLO/S Hermann Wall-er GEHLEN Nov. 28, 1961 J. GILLOIS ET AL 3,010,128

MOBILE SELF PROPELLED BRIDGE UNITS Filed June 3, 1957 8 Sheets-Sheet 3 INVEN 1'01? 8 Jean GILL 0/5 Herm ann Walt-er GEHLE N Aq-av 8 Sheets-Sheet 4 J. GlLLOlS ETAL MOBILE SELF PROPELLED BRIDGE UNITS Nov. 28, 1961 Filed June 3, 1957 Nov. 28, 1961 J. GILLOIS ETAL MOBILE SELF PROPELLED BRIDGE nuns 8 Sheets-Sheet 5 Filed June 3, 1957 Nov. 28, 1961 J. GILLOIS ETAL MOBILE SELF PROPELLED BRIDGE UNITS Filed June 3, 1957 8 Sheets-Sheet 6 INVEN TO 7- S Jean GIL L 0 I6 Hermann Wall-er GEH L EN Nov. 28, 1961 Filed June 3, 1957 J. GlLLOlS ET AL 3,010,128

MOBILE SELF PROPELLED BRIDGE nuns 8 Sheets-Sheet 7 IIIIIIIIIIIIIIIIIIIIIIIIII'IIIIIIIIllIIIIIllI/I Evil/1111111111111!!! fie l IIIIIIIIIIIIIIIIIIIIIIII.

VIIIIIIIIIIIIIIII IN VEN TO 7-?8 Jean G/LLO/S Hermann Valfer GEHL EN ayM/W Nov. 28, 1961 J. GILLOIS ETAL MOBILE SELF PROPELLED BRIDGE UNITS 8 Sheets-Sheet 8 Filed June 3, 1957 IN VEN r0 1-?8 m 61.. n mm United States i atenr MOBILE SELF PROPELLED BRIDGE UNITS Jean Gillois, Rastatt, Germany, and Hermann Walter Gehlen, 6t) Pirmasenser Strasse, Kaisersiautern, Main,

Germany, assignors, by mesne assignments, to Hermann Waiter Gehlen, Kaisersiautern, Plain, Germany Filed June 3, 1?57, Ser. No. $36,262 Claims priority, application Germany dune 4, 1956 7 Claims. (Cl. 14-1) The present invention relates to mobile self-propelled bridge units.

Numerous proposals are already known for the rapid installation or assembly or bridge in situ. In the case of the majority of mobile self-propelled bridges or bridge units these proposals are restricted to light structures of scissor-like form and which have comparatively small spans for use by light loads. While mobile the scissorlike structures are closed, but on the site of their operation they are opened over the obstacle to be surmounted.

Locomotive bridges are also known wherein a finished steel superstructure is mounted by means of rolling segments in the centre of two floating track vehicles and is provided with devices for the coupling of other steel superstructures, while the first and the last unit of a bridge of this kind has extensible ramps.

The object of the present invention is to provide a mobile self-propelled and rapidly erectile bridge for use on land, which is constructed with the least possible amount of material yet enables steep precipices, comparatively large uneven stretches of ground, cuttings, smaller rivers, brooks and the like to be rendered negotiable to vehicles or to be otherwise bridged.

This object is achieved in accordance with the present invention by a mobile self-propelled bridge unit and having a main bridge component consisting of two main girders interconnected or spanned by a roadway, and at either or both ends of which component ramps, preferably of different lengths, are hinged so as to be flapped over on to the deck of the bridge during travel to and from sites of use and to extend beyond the ends of the bridge during use.

Conveniently there is inserted between the lower boom or girder of each ramp and the main bridge component a hydraulically, pneumatically, mechanically or electrically actuated system of rods, by means of which the ramps are swung out into the operative position and can either both be fixed at predetermined inclines to the roadway or in the same direction as the roadway so that the main bridge component and its hinged ramps form a rigid composite bridge unit.

It has proved to be particularly advisable to provide additional locking of the ramps and the main component in their trafiic accommodating position, by means of bolts engaging in eyes of butt straps for relieving the actuating rods of the ramps of unnecessary load. The locking bolts may be actuated mechanically or hydraulically from the drivers cabin for various positions of the ramp. The advantage of this construction is that the strength of the actuating rods for the ramps should be suficient for ensuring the folding operation of the ramps leaving the load created by trafiic on the bridge to be taken care of by the bolts.

In the case of a bridge unit having ramps movabl fitted at both ends, it is possible to utilise two drives in displacing each or" the ramps, the centers of rotation of which are displaced relative to each other so that upon the moving of a ramp into a zero position with the ramp standing perpendicularly, one drive always continues to work and moves the ramp out of the zero position.

ere each of the ramps consists of two relatively displaceable parts, the second part may be moved in the same manner by means of two drives.

ice

The chassis and/or the axles of the unit may be retractable and extensible.

'In order to facilitate and simplify conveyance of the bridge unit in narrow streets and to render possible the loading of a bridge unit on to railway trucks with respect to the above-described clearances, the bridge unit may be relatively narrow but with laterally extensible attachments for widening the roadway of the unit when in use.

The bridge unit may be so constructed that it is adapted to float, i.e. in the manner of a pontoon. By this means it is possible to move vehicles across a river and to assemble them on the opposite bank thereof without having to use a bridge structure.

Further features of the invention and details of the advantages achieved thereby will be apparent from the following description'of embodiments of bridge units illustrated in the accompanying drawings in which:

FIGURES 1 and 2 illustrate in side and front elevation respectively one form of bridge unit according to the invention.

FIGURES 3-7 show diagrams of difierent possible uses of the bridge unit.

FIGURES 8, 8a and 9 show a bridge unit having bipartite ramps in the operative position and in the travelling position.

FIGURES 10 and 11 aredetails illustrating the locking of the ramps together with the main bridge component.

FIG. 12 is a longitudinal section of the vehicle shown in FIG. 9 having a front and a rear ramp, each of which is made of two parts.

FIG. 13 is a side view of the vehicle shown in FIG. 12 showing different positions of the larger of the two ramps.

FIGURES l4 and 15 show, in plan and in cross section, an attached portion hooked to the main bridge unit for the purpose of widening the unit driving use.

FIGURES 16 and 17 show in cross section an attachment, consisting of pivotable brackets and a drag sheet, respectively in the inoperative and withdrawn positions.

FIGURES 18 and 18a show a bridge constructed of several units with under-tensioning means for connected units.

FIGURES l and 2 diagrammatically represent a bridge unit in its simplest form. The main body of the unit is shown at I and comprises a pair of main girders 3'7 and an interconnecting roadway 36. A relatively long ramp 2 and a shorter ramp 3 are linked to the main body 1 at opposite ends thereof. The vehicle has its own drive 4 and retractable wheels 5.

When in transit, the

ramps

2, 3 are folded over the road surface or deck of the main bridge body 1. The vehicle is driven to the uneven stretch of land, the brook, the steep precipice or the like site of operation, whereupon the two ramps are unfolded so as to project beyond the ends of the main body. The movement of the ramps may be achieved hydraulically, pneumatically, mechanically orelectrically, and the drive for this is such that a folding angle of about 200 may be obtained.

In the embodiment shown in FIGURE 1, the movement of the ramps is effected by hydraulically controlled rods 6. These are so constructed that the ramps may be fixed at any desired incline relatively to the roadway of the bridge.

FIGURES 3-7 are illustrative of various possible uses of a mobile bridge unit having two approach ramps at its opposite ends. The bridge unit first approaches the obstacle to be bridged, which in FIGURES 3 and 4 is a ditch A, near enough for the unit to project partly over the ditch. The front and rear axles are then retracted and the unit deposited on the ground. If the unit is intended to project as far as possible at the front, it is possible previously to unfold the ramp 3 at the back and to mount a counter weight thereon, for instance by using ballast or by anchoring the end of the ramp 3 or loading it with another heavy vehicle, such as a tank 8 (FIGURE 5). The forces to be absorbed by the ramp are transmitted through the hydraulically controlled rods 6 to the body of the bridge. The longer ramp 2 is then unfolded (FIGURE 6).

Rather small rivers of about 20 metres width may be bridged for example by driving the mobile unit into the river down the sloping bank thereof. Since the unit can float, this should be possible without difiiculty. After the unit has been deposited on the bed of the river the two ramps are unfolded with the ends of these ramps reaching the sloping banks. T he unit can then be raised with the hydraulic system of the ramps so that a bridge is formed between the two banks.

FIGURE 7 shows the use of a bridge unit for overcoming an obstacle in the form of a steep wall. For this purpose the unit is first brought into the position illustrated by broken lines. Then the centre portion with the two ramps is brought into an extended position by actuating the rod 6 between the large ramp 2 and the centre portion.

In order to relieve the rods 6 in the traflic position, the ramps and the bridge unit may, after they have been brought into the final position, be hydraulically locked together. This locking arrangement can be actuated from the drivers cabin for various positions of the ramp. It consists of butt straps 13 with eyes 14 arranged on the lower boom and which are engaged by butt straps 15 mounted on the ramp and having holes 16 (FIGURES 1 and 311). Locking is effected with the aid of a bolt 17 mechanically or hydraulically snapped into the

holes

14, 16 after the unfolding of the ramp. The rods 6 require to be of suflicient strength to ensure folding of the ramps and the raising of the bridge girder (FIGURE 7) where required while the locking mechanism, takes care of the forces arising from any loading of the bridge, such as by the passage of vehicles across it.

A development of the travelling bridge unit is illustrated in the embodiment shown in FIGURES 8 and 9. In this form of construction each of the two

ramps

2 and 3 is divided into two parts, those of the lenger ramp being shown at 2a and 2b and those of the shorter ramp at 3a and 319 respectively. For use in situ, the ramps are first unfolded together and then singly. The advantage of this arrangement is that more favourable conditions are obtained, particularly in use of the unit. In the case of a unit length of 11 metres for example, the ramp 2 instead of being say metres long may, in the embodiment shown in FIGURES 8 and 9, be formed of bipartite elements of eight and seven metres length making a total of metres when extended. Similarly the ramp 3 instead of being 4-5 metres in length could, when in two parts, have a length of 5+6 metres, i.e. 11 metres in all. In the result, longer spans may be bridged by the unit of FIGURES 8 and 9. The unfolding of the two ramp members may be effected mechanically or hydraulically.

The bridge unit illustrated in FIG. 12 is constructed essentially in the same manner as the bridge units of FIGURES l-ll. For better support and for an improved distribution of forces, particularly when a comparatively lengthy wheel span is required, a pair of disc wheels 10 as shown in FIGS. 12, 18 and 1811, which may be raised and lowered at will, are provided on both longitudinal sides approximately in the middle of the vehicle. In FIG. 12 these wheels are merely indicated on the remote side of the vehicle and in interrupted lines to provide for clearness.

The front and rear ends of the vehicle in accordance with FIGS. 9, 12 and 13 is provided with hinge means 7 to which

ramp portions

2a, 2b, 3a and 3b are pivotally secured. The forward and topmost ramp members or girders 2b and 3b are secured at their lower girder portions to the

ramp portions

2a and 30, respectively, by means of shafts 52. The lateral attachment members 21.

for widening the roadway are stored on and securely fastened to the ramp portion 31) during street travel.

The propulsion of the vehicle is effected by the motor means 53 which transmits the driving power to the rear axle 33 and if desired also to the front axle 39. The steering takes place from the drivers cab 40 by Way of steering column 41 and the shafts 43 which are passed over the forward wheel housing 4-2, and connected to the steering gear of the axle 39.

The wheel assemblies 44 can be retracted into the completely closed wheel housings or chambers 42. Axles 38 and 39 are connected for this purpose by means of springs 45 to pivotable frames 46. Frames 46 in turn are pivotally mounted at joints 47 on the vehicle body 1. For street travel the free ends of the pivotable frames 46 are securely locked by means of hydraulic or other mechanical latches 48 on the body of the vehicle. It is thus possible to let out or retract the entire driving assembly, upon release of the latch members 48, with the hydraulic two-way operating cylinders 49.

It will be apparent from FIG. 12 that it is possible by means of hydraulic cylinder 49 to extend the wheel assemblies 44 sufficiently far to permit tire changing, thus eliminating the necessity of special recesses in the walls of the wheel chambers. Complete retracting of the wheel assemblies removes any tratfic loads from the axles when the vehicle is deployed as a bridge span.

The

hydraulic cylinders

6 and 6"are pivotally mounted on the vehicle body while the piston rods thereof are linked to the ramp halves 2a and 2b and 3a and 3b. The hydraulic cylinders 6' are each connected at one end to the ramps and their piston rods are pivotally connected to special pivot arms 50 which in turn are rotatably journalled on the ramp pivot rods 52 for movement independently of the ramp. The pressure fluid for moving the ramp cylinders is supplied by the fluid pump 51 which is mounted on a flanged portion of the engine or prime mover '37. The control of the ramp movement is effected by a hydraulic control provided in the drivers cab 40.

The swinging operation of the

ramps

2 and 3 is the same for both ramps and is described hereinafter with reference to ramp 2. The vehicle in street travel condition is driven into close proximity of the gap or recession in the terrain and the wheel assemblies are completely retracted to engage the bottom of the vehicle body with the ground. The two ramp sections 2a and 2b are swung out in folded condition by means of the hydraulic cylinder 6 until the axis of the cylinder is positioned shortly ahead of the center point of the hinge '7 of the lower connection of the ramp portion 2a with the vehicle body, which is the dead center position shown in full lines in FIG. 13.

Since ramp cylinder 6 now has no leverage to apply force to the hinge 7, further swinging of the ramp cannot be effected by means of this cylinder alone. Therefore the forward ramp portion 2b is swung forwardly by the hydraulic operating cylinder 6' to an extent of about -90, as illustrated in FIG. 12. As a result the center of gravity of the two ramp halves 2a and 2b is shifted forwardly so that the entire ramp swings forward under its own power. To prevent the ramp from dropping freely the ramp cylinder 6 acts as a brake during this phase of the movement. For this purpose an over-pressure valve is connected to the cylinder 6 which regulates the maximum pressure and therefore the braking moment. Continued swinging movement of the forward ramp portion 2b by means of the hydraulic cylinder 6' and continued yielding of cylinder 6 results in the completely stretched position of the ramp over the gap in the terrain. Upon extending the rear ramp 3:: and 3b in the same manner it is now possible for heavy caterpillar and wheel vehicles to travel over the rapid deploying bridge.

Cylinder 6 of the large ramp 2a, 2b establishes a rigid connection between the ramps and the body of the vehicle after locking of the hydraulic control. It is possible to construct the cylinder also in a manner that it remains movable so that the connection of the ramps with the vehicle body is movable. It is also possible to supply the hydraulic fluid to the other side of the piston of cylinder 6 thereby obtaining upward pressure against the vehicle body to bridge steep slopes as shown in FIGS. 7 and 8.

The returning or retracting of the large ramp 2a and 2b takes place in a sequence which is opposite to the outward swinging operation, except for the swinging across the dead center position where the forward ramp portion 212 remains in the stretched position. In this manner the center of gravity of theramp is shifted rearwardly so that the return swinging movement is possible.

By coupling together the various embodiments of bridge units, land irregularities caused by streams, small rivers and the like can be bridged in a very short time and practically without any appreciable assembly ditriculties.

FIGURES 14l7 show details of construction of attachments for widening the roadway of a mobile bridge unit.

In the embodiment shown in FIGURES 14 and 15 the component 1 of a mobile bridge unit having its own drive, has at the sides of its deck or roadway recesses 18 which are bridged in the outermost corner of the unit by a short round iron bar 19 welded, or secured in any other manner, to the wall of the bridge unit. Attachments 21 for widening the roadway are hooked to the bar 19 by means of hooks 20. These attachments 21 are supported by their lower portion engaging directly against the wall of the bridge unit or with the insertion of a plate or butt strap 22. Each attachment is constructed as a hollow girder and has an upstanding part 23 constituting a scraping edge.

In the embodiment shown in FIGURES 16 and 17, a number of vertically disposed bolts 25 are arranged along the side or longitudinal Walls 24 of the bridge component 1 to operate as pivots for brackets 26. A drag sheet 27 is secured by means of a bolt 28, to the free end of the brackets remote from the pivots 2 5. The drag sheet is kinked in cross section at 2? over the place of its attachment to the free end of the bracket 26. By this kink 29 the drag sheet 27 is disposed on the horizontal flange 30 of an angle iron 31 extending axially of the bridge component, and is thereby mounted slightly resiliently. Similarly, the bolt 28 holding the drag sheet is resiliently secured in its longitudinal axis by a helically wound spring 32. In the withdrawn position, the drag sheet, with its free longitudinal edge, is disposed on a butt strap 33 se cured to the bridge unit so that the inner edge of the drag sheet lies in the plane of the road surface of the main bridge component 1.

For swinging in the unfolded brackets together with the drag sheets, these are raised to the roadway of the bridge by means of a hook. The brackets can then be swung about the pivots 295 into recesses in the upper part of the bridge. The free end of the drag sheet is provided with a projection 34 which engages when the brackets are in-the inoperative position, in an aperture in'the roadway of the main portion of the bridge and retains the brackets and the drag sheet in the inoperative condition. The outside of the angle iron 31 is provided with a scraping edge 35.

In order to achieve the greatest possible supporting length, coupled bridge components may be under-or overtensioned, for example as illustrated in FIGS. 18 and 18a. Cables 12. controlled by a winch are provided for this purpose. By suitably guiding the cables, trafiic loads may be absorbed in the case of under-tensioning and, in the case of over-tensioning, favourable efiects are achieved when the front length is extended unsupported. In the case of under-tensioning, the tension cables 12 (FIGS. 18 and 18a) are guided over a pair of disc wheels projecting beyond the base of the unit. For over-tensioning purposes, a non-illustrated system of rods actuated hydraulically, mechanically or in any other manner, is provided with a pulley for guiding the cable.

We claim:

l. A mobile self-propelled unitary structure defining a bridge unit in the form of a floating body having a main body comprising generally parallel side members, an interconnecting roadway extending intermediate said side members, a prime mover, actuating means associated with said prime mover and retractable wheels operatively associated with said actuating means and disposed generally within the confines of said side members, said body being provided at least at one end thereof with rigid connecting means in the form of supporting hinge means or the like, a ramp having corresponding hinge means on that part thereof which is lowermost for the position of rest of said ramp on said main body, said corresponding hinge means being connected to said supporting hinge means, and power actuated rods or the like associated with said actuating means disposed intermediate said main body and a part of said ramp proximate said hinge means, whereby said ramp is angularly displaceable into fixed operative positions at predetermined inclines endwise of said roadway to constitute a continuous track defined by said roadway and said ramp, said body and ramp including interengaging straps or thet like having apertures, and bolts operative to extend through said apertures, thereby locking said ramp in adjusted position relative to said body and relieveing the actuating rods.

2. A mobile self-propelled unitary structure defining a bridge unit in the form of a floating body having a main body comprising generally parallel side members, an interconnecting roadway extending intermediate said side members, a prime mover, actuating means associated with said prime mover and retractable wheels operatively associated with said actuating means and disposed generally within the confines of said side members, said body being provided at least at one end thereof with rigid connecting means in the form of supporting hinge means or the like, a ramp having corresponding hinge means on that part thereof which is lowermost for the position of rest of said ramp on said main body, said corresponding hinge means being connected to said supporting hinge means, and power actuated rods or the like associated with said actuating means disposed intermediate said main body and a part of said ramp proximate said hinge means, whereby said ramp is angularly displaceable into fixed operative positions at predetermined inclines endwise of said roadway to constitute a continuous track defined by said roadway and said ramp, said body and ramp including interengaging straps or the like having apertures, and bolts operative to extend through said apertures, thereby looking said ramp in adjusted position relative to said body and relieving the actuating rods, and automatic operating means for said bolts associated with said actuating means.

3. A mobile self-propelled unitary structure defining a bridge unit in the form of a floating body having a main body defined by generally parallel side members, an interconnecting roadway extending intermediate said side members, a prime mover, actuating means associated with said prime mover, and retractable wheels operatively associated with said actuating means and disposed generally within the confines of said side members, said body being provided at least at one end thereof with rigid connecting means in the form of supporting hinge means or the like, a ramp having corresponding hinge means on that part thereof which is lowermost for the position of,rest of said ramp on said main body, said corresponding hinge means being connected to said supporting hinge means, and power actuated rods or the like associated with said actuating means disposed intermediate said main body "and :a part of said ramp proximate said hinge means, whereby said ramp is angularly displaceable into fixed operative positions at predetermined inclines endwise of said roadway to constitute a continuous track defined by said roadway and said ramip, said ramp being defined by a lower and an upper boom, said corresponding hinge means being provided on said lower boom and said rods of said power actuated means being connected to that part of said lower boom which is uppermost for the position of rest of said ramp on said roadway.

4. A mobile self-propelled unitary structure defining a bridge unit in the form of a floating body having a main body comprising generally parallel side members, an interconnecting roadway extending intermediate said side members, a prime mover, actuating means associated with said prime mover and retractable wheels operatively associated with said actuating means and disposed generally within the confines of said side members, said body being provided at least at one end thereof with rigid connecting means in the form of supporting hinge means or the like, a ramp having corresponding hinge means on that part thereof which is lowermost for the position of rest of said ramp on said main body, said corresponding hinge means being connected to said supporting hinge means, and power actuated rods or the like associated with said actuating means disposed intermediate said main body and a part of said ramp proximate said hinge means, whereby said ramp is angularly displaceable into fixed operative positions at predetermined inclines endwise of said roadway to constitute a continuous track defined by-said roadway and said ramp, said ramp being defined by a lower and an upper boom, said corresponding hinge means being provided on said lower boom and said rods of said power actuated means being connected to that part of said lower boom which is uppermost for the position of rest of said ramp on said roadway, said power actuated means comprising said rods and fluid operated pistons, and each of said parts of said ramp having two drives, the center of rotation of each of said drives being displaced in a manner that in operation, upon reaching substantially vertical zero position, one of said drives continues to operate to move the ramp out of said zero position.

5. A mobile self-propelled unitary structure defining a bridge unit in the form of a fioating body having a main body comprising generally parallel side members, an interconnecting roadway extending intermediate said side members, a prime mover, actuating means associated with said prime mover and retractable wheels operatively associated with said actuating means and disposed generally within the confines of said side members, said body being provided at least at one end thereof with rigid connecting means in the form of supporting hinge means or the like, a ramp having corresponding hinge means on that part thereof which is lowermost for the position of rest of said ramp on said main body, said corresponding hinge means being connected to said supporting hinge means, and power actuated rods or the like associated with said actuating means disposed intermediate said main body and a part of said'ramp proximate said hinge means, whereby said ramp is angularly displaceable into fixed operative positions at predetermined inclines endwise of said roadway to constitute a continuous track defined by said roadway and said ramp, said unit having recesses along the upper outer longitudinal edges bridged by round iron bar members and elongated attachments having hook conformations in engagement with said iron bar members and presenting upper substantially horizontal surfaces extending laterally of said roadway, thereby widening said roadway.

6. A mobile self-propelled unitary structure defining a bridge unit in the form of a floating body having a main body comprising generally parallel side members, an interconnecting roadway extending intermediate said side members, a prime mover, actuating means associated with said prime mover and retractable wheels operatively associated with said actuating means and disposed generally within the confines of said side members, said body being provided at least at one end thereof with rigid connecting means in the form of supporting hinge means or the like, a ramp having corresponding hinge means on that part thereof which is lowermost for the position of rest of said ramp on said main body, said corresponding hinge means being connected to said supporting hinge means, and power actuated rods or the like associated with said actuating means disposed intermediate said main body and a part of said ramp proximate said hinge means, whereby said ramp is angularly displaceable into fixed operative positions at predetermined inclines endwise or" said roadway to constitute a continuous track defined by said roadway and said ramp, said unit having recesses along the upper outer longitudinal edges bridged by round iron bar members and elongated attachments having hook conformations in engagement with said iron bar members and presenting upper substantially horizontal surfaces extending laterally of said roadway, thereby widening said roadway, and having outer ends raised relative to said roadway to form a scraping edge.

7. A mobile self-propelled unitary structure defining a bridge unit in the form of a floating body having a main body comprising generally parallel side members, an interconnecting roadway extending intermediate said side members, a prime mover, actuating means associated with said prime mover and retractable wheels operatively associated with said actuating means and disposed generally within the confines of said side members, said body being provided at least at one end thereof with rigid connecting means in the form of supporting hinge means or the like, a ramp having corresponding hinge means on that part thereof which is lowermost for the position of rest of said ramp on said main body, said corresponding hinge means being connected to said supporting hinge means, and power actuated rods or the like associated with said actuating means disposed intermediate said main body and a part of said ramp proximate said hinge means, whereby said ramp is angularly displaceable into fixed operative positions at predetermined inclines endwise of said roadway to constitute a continuous track defined by said roadway and said ramp, said unit being provided with a plurality of perpendicularly disposed pivot bolts secured to the longitudinal outer sides thereof and a plurality of brackets, one mounted on each bolt, said brackets being movable about said bolts and having each a fastening belt at the free end thereof and drag sheets mounted endwise of said brackets by means of said bolts and being movable outwardly with said brackets to widen said roadway.

References Cited in the file of this patent UNITED STATES PATENTS 1,289,880 Newman Dec. 31, 1918 1,447,893 Roy Mar. 6, 1923 2,282,519 Holmes May 12, 194-2 2,449,829 Agren Sept. 21, 1948 2,543,054- Peter Feb. 27, 1951 2,556,175 Frost m June 12, 1951 2,711,803 Hurst June 28, 1955 FOREIGN PATENTS 785,137 France May .13, 1935 1,112,888 France Nov. 23, 1955