US2296418A - Indicator for finishing-machine screeds - Google Patents

Description

Sept. 22, 1942. J. E. BUSHNELL INDICATOR FOR FINISHING-MACHINE SCREEDS Filed Dec. 2, 1941 2 Sheets-Sheet l lNVENTOR (James Efiushne/l a w w Ema/ A 0W4 P 1942 J. E. BUSHNELL 2,296,418

INDICATOR FOR FINISHING-MACHINE SCREEDS Filed Dec. 2, 1941 2 Sheets-Sheet 2 fig. 4

INVENTOR James TBus/me If m and M Patented Sept. 22, 1942 INDICATOR FOR FINISHING-MACHINE SCREEDS James E. Bushnell, Aspinwall, Pa., assignor to Blaw-Knox Company, Pittsburgh, Pa., a corporation of New Jersey Application December 2, 1941, Serial No. 421,327

6 Claims.

This invention relates to an indicator for finishing-machine screeds and, in particular, to a device for indicating the crown or degre to which a deformable screed has been forcibly caused to assume a curved condition.

Deformable screeds for finishing machines are well known, a typical form thereof being shown in French Patent 1,995,450. This patent also discloses an indicator intended to show at aglance the extent of deformation of the screed. There are certain objections, however, to the indicator shown in said patent and it is the object of my invention to provide an improved indicator con-: struction which overcomes such disadvantages. Among the latter is the fact that th French in-- dicator is not accurate because the relatively fixed member thereof is mounted on a portion of the screed which is subject to the forces applied to deform the troweling surface, and, though theoretically rigid, is practically deformable even when constructed of heavy members. Such members, furthermore, are not equally deformable in different machines so it is not possible to make a uniform allowance for variation from the true indication. The indicator of the French patent,. moreover, moves with the screed which oscillates longitudinally and is, therefore, rather difficult to read during operation.

I have invented a novel indicator for finishingmachine screeds which is not subject to the short-' comings mentioned above. In a preferred embodiment, I provide an indicator including a relatively fixed member mounted on the frame of a finishing machine which, relatively speaking, is quite rigid and not subject to the forces exerted on the screed to deform it to crowned contour. I also provide a relatively movable member or gage cooperating with the fixed member to provide a visible indication. The gage is positioned by the elevation of the screed at a point adjacent the center thereof. I also provide means on the screed for supporting the gage without imparting to the latter the longitudinal movement of the screed.

Further details of the invention and the advantages thereof will be made more apparent during the following complete description which refers to the accompanying drawings illustrating the above-mentioned preferred embodiment. In the drawings,

Figure l is a plan view showing certain portions of a finishing machine and its screed with parts omitted for the sake of clearness;

Figure 2 is a sectional view taken along the plane of line IIII of Figure 1 showing the ingether by cross plates (not shown).

dicator, the screed and its supporting structure in elevation;

Figure 3 is a sectional view taken along the plane of line IIIIII of Figure 2 showing the indicator in side elevation, and

Figure 4 is an elevation of a detail.

Referring now in detail to the drawings, the indicator of my invention shown generally at H] is mounted on a finishing machine which may conveniently be of the general type shown in 0rd Patent 1,522,138, including spaced end-frames ll adapted to travel along the side forms or road rails between which a pavement slab is cast, the end frames being connected by main transverse members such as front and rear beams [2. In the particular form of finishing machine partially shown in the drawings, the members I2 are secured .to brackets 13 fastened to the ends of the end frames II. It will be understood that the finishing machine also includes a power unit such as an internal-combustion engine and the necessary control and transmission devices for driving traction wheels carried in the end frames and for operating a transversely extending screed which is mounted on the machine for reciprocation longitudinally, i. e., transversely of the pavement slab. My invention, however, does not concern such details and they are, therefore, omitted. The screed itself is shown generally at [4 and is preferably of the type disclosed in the French patent aforementioned, including a relatively rigid supporting member [5 and a deformable troweling member [6 .therebelow. The supporting member 15 is composed of a pair of channels secured to- The troweling member [6 is also a channel disposed with its flanges upwardly.

The French patent fully discloses the means for deforming the troweling member 16, including tension links, bell cranks and take-up means such as a turn-buckle. Of the latter, only the turnbuckle is shown at H and the tension links at 18 and IS. The turn-buckle is supported in a bracket 20 secured to the screed support I5. By operating the turn-buckle IT in one direction or the other, the troweling member 16 on the screed is forcibly caused to assume a curved condition or is permitted to return to its normal, relatively straight condition, by the means and in the manner fully disclosed in the French patent.

A driving pin 2| extends through the supporting member I5 of the screed at about the midpoint thereof. The pin passes through alined holes in the webs of the channels forming the member 15 and also in a plate 22 and an auxiliary channel 23 welded thereto, to provide a bearing of greater length. The rear end of the pin is machined as at 24 for the attachment of a pitman for reciprocating the screed.

The structure described above is known, at least generally, and it now remains to describe in detail the indicator of my invention as applied to the finishing-machine construction outlined above.

A support in the form of a channel 25 extends forwardly from the frame of the machine, being carried on the forward cross-member I2. An auxiliary channel 25 extends laterally from the channel 25 on the upper flange of the beam I2 and is secured to the channel 25 by an angle bracket 2'1. An auxiliary channel 28 extends laterally from the channel 25, being secured thereto by an angle bracket 29. A plate 30 rests on and is welded to the channels 25 and 28. The channel 2% is connected to another channel (not shown) similar to channel 25 extending forward.- ly from the front cross-member I2. By virtue of the construction describedthe channel 25 is supported. from the main frame of the machine which is relatively quite rigid, and is fixed vertically relative to the slab being finished.

A socket 3I is secured to the flange of the channel 25 and supports a pivot bearing shaft 32 extending laterally therefrom. A gage plate 33 is mounted on the shaft 32. As shown in Figure 3, the plate 33 has bent-up flanges 34 with. alined holes therethrough adapted to receive the shaft 32..

A gage 35 is movable relative to the plate 33. The gage is. in the form of. a post or staffv slidably confined against the plate. 33 by guides 35. The guides are secured to the gage plate. by bolts having spacer sleeves thereon. The. upper end ofthe gage moves. past a graduated scale 33- The scaleis secured to the gage plate by bolts39 passing through a slot M3 extending. vertically ofthe plate 33.

A gage. track 4 I in the form of an upwardly extending plate having a horizontal upper edge is secured to a spacer plate 12v bolted tothe rear flange of the channel forming the troweling member it of the screed. A clevis- 43. secured to the lower end of the gage 35 has a wheel or roller 44 journaled thereon which bears on the track II. By the construction and arrangement of the parts illustrated and described, it will be evident that the upper end of the gage 35 is positioned relative to the scale 38 in accordance with. the elevation of the troweling member I6 of the screed at the point at which the gage track M is secured. As indicated by its position relative to the turn-buckle II, the gage track is located adjacent the mid-point of the length of the screed. It will also be apparent that as the screed reciprocates the gage track moves with it. On such reciprocation, the track 4| travels below the wheel it, the gage being maintained in vertical position by the guides 36 and free for vertical movement, without binding.

When the troweling member I6 of thescreed is adjusted from a relatively straight to a curved condition by operation of the turn-buckle II, the mid-portion of the member I6 is elevated. since the ends thereof are maintained at a fixed elevation, i. e., in contact with the road rails, regardless of whether a flat or crowned slab is being finished. As the member I 6 is archedor crowned, the gage rises accordingly and the position of the upper end thereof relative to the scale 33 indicates the magnitude ofthe crown, i. e., the ele-- vation of the mid-portion of the member I6 relative to the end portions thereof. The crown to which a pavement slab is finished is usually designated by the height in inches of the mid-portion of the pavement above the edges and the scale 38 may, therefore, be conveniently graduated in inches as shown in Figure 4.

It will be apparent from the foregoing that the invention is characterized by numerous advantages over screed indicators as known heretofore. In the first place, the fixed member of the indicator, 1. e., the gage plate 33, is mounted on a fixed and relatively nondeformable structure, the frame of the finishing machine. The mov able member, i. e., the gage 35, is positioned in accordance with the elevation of the mid-portion of the troweling member of the screed above the ends thereof which in turn depends upon the adjustment of the screed-flexing mechanism. The degree of arch or crown imparted to the screed is indicated directly by. the position of the'top' of the; gage 35 relative to the graduated scale 38"and these parts are so positioned as to. be readily visible to the operator of the machine. Observation of. the indicator is facilitated by the fact that the indicator does not oscillate with the screed but remains stationary. The accuracy of the indication, furthermore, is not af:

fected by the reciprocation. The pivotal mount.- ing of the gage plate provides accommodation for any slight back-and-forth movement of the screed and its support as a Whole and prevents bending or binding of the gage 35.

The construction of the indicator of my invention is simple and relatively inexpensive; The indicator, furthermore, does not interfere with the normal operation of the finishingv machine. Screeds such. as that of the. French. patent, for example, are usually mounted so: they can be lifted clear of the pavement and side rails for backward movement of the machine prior to a second pass over the slab being finished. Such operation is permitted by my indicator since it results merely in the gageamoving upwardly above its normal position. This furnishes an indication to the operator, at a. glance,.whether the screed is raised or lowered, even though it is not in the direct range of his vision The. adjustability of the scale 38 makes it. possible. to calibrate the indicator readily, despite variations between different machines resulting from the usual manufacturing tolerances or any permanent. deformation of the frame although the lat.-

ter is not likely to occur.

Although I have illustrated and described but a preferred embodiment of my invention, it will be recognized that changes in the construction and arrangement of parts may be made without departing from the spirit of the invention or the scope of the appended claims.

I claim: 7

1. An indicator for a finishing machine including a main frame, a transverse screed and crownadjusting mechanism for said screed, said indicator comprising a substantially vertical member secured to said frame and a gage movable relative thereto, and means mounted on said screed and moving therewith providing a horizontal bearing surface effective to support said gage in various positions, depending on the elevation of the screed at the point where said means is located. 7

2. An indicator for use ona finishing machine including a rigid, relatively hon-deformable frame, adeformable screed extending transverse ly thereof, and means for deforming the screed to different degrees of curvature, said indicator comprising a gage plate supported on said frame, a gage movable along said plate, and a horizontal bearing surface on said screed supporting said gage in a position determined by the elevation of the screed at the point where said means is located.

3. An indicator for use on a finishing machine including a rigid, relatively non-deformable frame, a deformable screed extending transversely thereof, and means for deforming the screed to different degrees of curvature, said indicator comprising a gage plate supported on said frame, a gage movable along said plate, and a gage track on said screed, said gage resting on said track.

4. An indicator for use on a finishing machine including a rigid, relatively non-deformable frame, a deformable screed extending transversely thereof, and means for deforming the screed to different degrees of curvature, said frame being adapted to be supported on rails between which an area is to be paved, said indicator comprising a gage plate supported on said frame, a gage reciprocable vertically of said plate, and means on said screed providing a track supporting said gage in a position determined by the elevation of the screed at the point Where said means is located, above said rails.

5. An indicator for use on a finishing machine including a rigid, relatively non-deformable frame, a deformable screed extending transversely thereof, and means for deforming the screed to different degrees of curvature, said indicator comprising a gage plate supported on said frame, a gage reciprocable vertically of said plate, and a gage track on said screed, said gage resting on said track.

6. An indicator for use on a finishing machine including a rigid, relatively non-deformable frame, a deformable screed extending transversely thereof, and means for deforming the screed to different degrees of curvature, said indicator comprising a relatively fixed vertical member, means pivotally mounting said member on said frame, a relatively movable gage cooperating with said vertical member to provide a visible indication, and means on said screed providing a track whereby said gage is supported in a position determined by the degree of deformation of the screed.

JAMES E. BUSHNELL.

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