US1648574A

US1648574A - Operating mechanism for movable bridges and the like

Info

Publication number: US1648574A
Application number: US756879A
Authority: US
Inventors: Jr Thomas E Brown; William G Williams; Hardesty Shortridge
Original assignee: Individual
Current assignee: Individual
Priority date: 1924-12-19
Filing date: 1924-12-19
Publication date: 1927-11-08
Anticipated expiration: 1944-11-08

Description

Nov. 8, 1927. 1,648,574

T. E. BROWN, JR., ET AL OPERATING MECHANISM FOR MOVABLE BRIDGES AND THE LIKE Filed Dec. 19, 1924 4 Sheets-Sheet l anvenbovs Nov. 8, 1927.

T. E. BROWN, JR., ET AL OPERATING MECHANISM FOR MOVABLE BRIDGES AND THE LIKE Filed Dec. 19, 1924 4 Sheets-Sheet 2 Uvwenboiw Tfloms E, Bro w/v, Jr.

J WILL/HM 6. W11. LIAM/5 Qua 'KEUL 013 Nov. 8, 1927. 1,648,574

7 T. E. BROWN, JR., ET AL OPERATING MECHANISM FOR MOVABLE BRIDGES AND THE LIKE Fil ed Dec. 19, 1924 Q 4 Sheets-Sheet s nbom W11. L MM 6. Wu. L lmvs a R TIP/D65 M12055 T) Uwvewtor/ 7i/0Mfl5 E. BROWN, J/E.

4 Sheets-Sheet 4 T. E. BROWN, JR., ET AL OPERATING MECHANISM FOR MOVABLE BRIDGES AND THE LIKE Filed Dec. 19. 1924 Nov. 8, 1927.

WILL/HM. 6. WILL/4M5 HOETRIDGE HHRDESTY az WW e1 WWW/QM?- ment in the location of the holding-down.

ing parts

31 and 32 since both of these travel at the same rate, neither sliding with reference to the other. This method of supporting the rack is separately advantageous, and is particularly advantageous in connection with the other features referred to herein. The rollers are proportioned to carry the weight of the members 13 and connected parts in all of their positions during the movement of the span, and the shaft 17 is proportioned to carry the loadof the rollers, as well as the stresses of the pinion tooth pressures required for operation.

The rollers 29 are holding down rollers of the several channels 13. And if we regard these several channels as a single member,

we may consider the rollers 29 as a single roller, since they are on a common axis and serve to hold down the several parts which carry the racks, and to hold the rack teeth in engagement with the pinions 16. And,

instead of two pairs of struts 13 straddling the frames and balancing the pressures, and

two pairs of holding-clown rollers 29, a sin gle strut, pinion and roller may be used for each truss, the trusses being properly braced to carry the eccentric application of the operating strut loads. Or a single strut and operating pinion and holding-down roller could be used for the entire span, connected at a point between the two trusses.

Ne have introduced a further improveroller 29 and in the shape of the operating strut or rack bar (in which term weaneluole the rack proper and the parts 1n which it is mounted). The outer or load-carryingend travels through an are 33, F1g. 3, 1n opening the bridge, this being an arc about the center of the pivot 2. The load-carrying end thus rises and falls causing an oscillation of the bar as it is moved longitudinally by the pinion.

"Fig. 4 shows the extreme angular positions of the bar; Ifthe depth of the bar, or the channels 13, were the same from end to end then its oscillation would cause a variation in the length of the portion of the bar lying on the imaginary line 3 1 between the centers of the pitch circle 31 on which it bears at one side and the holding-down roller 29 which it should just clear at the other side,

andthe bar would bind in some positions mbe too loose in other positions.

V le may limit this efiect to a minimum'by "qsetting the holding-down roller 29 slightly back of thevertical through the center of the'bearing rings 30 and to such an extent thatthe line 34 will be normal to the length of the bar in the half way position of itsoscillation: so that the departure from the normal will be the same for the starting position as for the opposite extreme angular position shown at 11*, Fig. 4. In these extreme positions the bar will occupy the maxslight allowance for mechanical inaccuracies, 1

the bar will always be prevented from coming out of proper engagement with the operating pinion but will not bind between thetwo rollers;

We prefer to make the bar straight along the lower edge, curving the upper edge to secure the necessary variation in depth, though either or both edges may be curved with the same-effect. And we prefer to secure the curvature by the use of a separate strip on top of the rack bar. Figs. 5 and 6 show this most clearly. On the top of each of the channels 13 is astrip of metal 35, the top of which is adapted for engagement, with the slight clearance shown, by the tread of the rollers 29. The upper edge of the strip 35 is on the curve (Fig. 5) calculated to maintain the distance between the top and bottombearings of the bar. The exact curve followed will depend upon the special circumstances of the case such as the location of supporting member 5 of the fixed frame. 1 The smgle-pinion 16 is mounted on the reduced outer end of the shaft and has a sleeve portion which carries one of the bearing rings 36, while the other bearing ring 37 is mounted directly on a part of the shaft 17.

The

rings

36 and 37 have their outer surfaces of the same diameter as the'pitch diameterof the pinion 16 and they form bearlugs for the plates on the lower edges of the girders 38 between which is mounted a rack Hill 15 driven bythe pinion 16. On the tops of the girders are plates 35 of varying thicle.

ness as in the previous figures and held down by the rollers indicated diagrammatically at 29. i

8 illustrates a construction which may be preferable where the parts of the tired frame which carries the pinion and holding down rollers may be separatedto allow the rack bar to pass between them and thus secure an arrangement of the pinion between two bearings. The parts 5 in thiscase are the parts of the fixed support corresponding Ill I 381 bearin of the rack bar.

assen to 5 in Fig. 1. They carry bearings for the shaft 17 ofthe pinion and for the upper shaft 28 of the holding-down rollers. strut is composed of two channels 13 Fig. 6 carrying between them the rack 15 in engagement with the pinion 16, and their lower flanges bear on rings 39 which are fixed on the pinion and correspond in diameter to the pitch line thereof. This figure illustrates a modification in the design of the up- On the face of each of the channels 13 there is mounted an angle 40 of light steel which is bent sothat its upper flange follows the desired curved as in contour. The curvature is comparatively slight. By punching the Web of the angle along the appropriate line it can be bolted or llVGt-GCll'O the channel 13 and at the same time bent to the desiredconto'ur.

Figs. 9 and 10 illustrate a construction embodying some, but not all, the features of our invention. Here the rack bar comprises 'a pair of channels 13 as in Figs. 5 and 6, with a rack 15 between them-engaging the pinion 16. The rings '39 constitute the lower hearing for the rack bar, as in previous fig ures, but the upper bearing is provided with two rollers 41 and located at different points in the length of the bar and mounted in triangular brackets 43 which are arranged to pivot about the shaft 1?. Thus when the rack bar oscillates the frames 43 will oscillate with it and the two ro'llers fl and 42 will 7 hold it down. Heretofore rack bars of this rollers respectively) in line along the underside of the bar, and these bearings haveoccupied considerable space and required a rather complicated framework to carry them and the same time avoid interference with the fixed supporting structure. We have secured a more compact, simpler and better construcsion by arranging the bearings for the underside of the bar atpoints axially in line with the pinion. This makes itpossible to use a shorter rack, which cuts down the cantilever load of the rack on the pinion and bearings when the span is open. It also carries the weight of the operating strut more directlvto the supports than was the case with the prior constructions.

P-y making these bearings of the same diameter as the pitch circle of the pinion, their is the added advantage that the rack bar will roll on these hearings without any sliding or frictional resistance; Thus these bearing rings may be of the simplest construction. lVhere the bearing surfaces cannot conveniently be arranged to correspond with the pitch circle'of the pinion, they may The pinion.

still be ar'anged on the axis of the pinion by making them int-he form of rollers capable' of rotary movement with'respec't to the This has the disadvantage of requiring hearings to facilitate the turning of the bearing rollers, but it preserves the adantages of location referred to above and may be sul istituted for the pitch line hearings in any of the arrangements described herein. And it will be unde tood that any usual or suitable method of f 11,. port on the underside of the rack bar may beadopied in connection with the fixed guide roller at the top and the rack bar of varying height along its length. In this case, evenwith a rocking supporting frame below, we avoid the necessity'of side 37 (Fig. 7) or indeed may he formed directi y on the shaft. Flanges may be provided as illustrated on the rollers-"or plates or other means used to guide the parts with a minimum lateral movement. The described hearings for the operating barmay be used with an operating pinion as described or with various other devices for reciprocating the bar.

Thou

h we have described with great particnlarity of detail certain embodiments of our invention, yet it is not to be understood therefrom that the invention is restricted to the particular embodiments disclosed. Various modifications maybe made by those skilled in the art without departure from the invention as defined in the following claims.

lVhat we claim is: p

1. An operating mechanism of the character described comprising an oscillating rack bar and apinion, said rack bar being supported at its lower edge, and a holdingdown device adapted to engage its upper edge, the depth of the rack bar varying at different points in its'length so as to maintain its upper edge in operative relation to said holding-down device in all positions of the bar. I

2. An operating mechanism of the character described comprising an oscillating rack bar and a pinion, supporting means acter described comprising an oscillating rack bar and a pinion, a supporting roller for the lower edge of the rack bar in line with the pinion and having a bearing surface of the same diameter as the pitch diameter of the pinion and a holding-down device adapted to engage the upper edge of the rack bar, the depth of the rack bar varying at different points in its length so as to maintain its upper edge in operativerelation to asid holding-down device in all positions of the bar.

4. An operating mechanism of the character described comprising an oscillating rack bar and a pinion and a bearing for the low-er edge of said bar located axially in line with the pinion, a fixed holding down device and a strip secured to said bar shaped? to engage said device inall positions of the bar. Y a

5. An operating mechanism ofthe character described comprising an oscillating bar, means for reciprocating the same and a bearing for the lower edge of said bar, said bearing being fixed against lateral movement and a fixed member constantly engaging the upper edge 01'' the bar during its reciprocating movements. v

6. An operating mechanism oi the char- .acter described comprising an oscillating ment; and a holding-down device adapted to engage the upper edge of the bar the depth of the bar varying at different points in its length so as to maintain its upper edge in operative relation to said holding- 'downdevice in all positions of the bar.

7. A bascule bridge in combination with an operating bar for the movable span there of, means for reciprocating said bar, a hearrack bar for operatingthe'movable span thereof, a pinlon for reclprocatmg sald bar,

a bearing for the lower edge of said bar located axially in line with the pinion hav ing a diameter equal to the pitch diameter of the pinion and a fixed holding-down device adapted to engage the upper edge of therack bar,the depth of'the rackbar varying-at different points in its length so as to maintain its upper edge in operative relation to said holding-down device in all positions ot the bar.

In witness "whereof, we have hereunto signed our-names.

THOMAS E. BROWN, JR. WILLIAM WILLIAMS. SHORTRIDGE} nannnsrv,

8. A bascule bridge in combination with a