US2999433A

US2999433A - Road finishing machine

Info

Publication number: US2999433A
Application number: US644134A
Authority: US
Inventors: Alphonse J Baltes
Original assignee: Individual
Current assignee: Individual
Priority date: 1957-03-05
Filing date: 1957-03-05
Publication date: 1961-09-12
Anticipated expiration: 1978-09-12

Description

Sept. 12, 1961 A. J. BALTES ROAD FINISHING MACHINE 3 Sheets-Sheet 1 Filed March 5, 1957 INVENTOR.

ALPHONSE J. BALTES Sept. 12, 1961 A. J. BALTES ROAD FINISHING MACHINE 3 Sheets-Sheet 2 Filed March 5, 1957 INVENTOR.

ALPHONSE J. BALTES Sept. 12, 1961 A. J. BALTES ROAD FINISHING MACHINE 3 Sheets-Sheet 3 Filed March 5, 1957 INVENTOR. ALPHONSE. J. BALTES BY I A/nlQa 4m QZQZ Fig. IO

Fig.9

nited States Patent ROAD FINISHING MACHINE Alphonse Baltes, 181 Benedict Ave, Norwalk, Ohio Filed Mar. 5, 1957, Ser. No. 644,134 8 Claims. (Cl. 94-45) The invention relates in general to road finishing machines and more particularly to road finishing machines having a screed in which the crown thereof is automatically adjustable.

In the laying of concrete roads and the like, road machines have been utilized for smoothing out the concrete and leaving the upper surface of the road with what is commonly referred to as a crown. If a stretch of pavemeat is said to have a crown, it means that the middle or center portion of the pavement is higher than either side in order that will drain from the road. In order to form the crown the road machine which is used to smooth the concrete must have a surface which is complementary to the crowned road surface as finished. The entire length of any given stretch of pavement, however, does not always have a crown. For example, when a curve is encountered, it is necessary to remove the crown from the pavement. A crown is undesirable on a curve since it is banked at an angle from the horizontal and water will drain therefrom easily and because the crown tends to subtract from the banked curve. In other words,

I the straight stretch of pavement will have a crown and as p it goes into a curve, the crown is gradually removed. It gis highly desirable that the crown be removed from the f pavement gradually, that is, in equal increments per linear 3 distance of pavement. In previous machines, the crown has been removed from such road finishing machines by having a workman gauge by eye the distance traveled and in turn mechanically adjust the crown by turning a crank as he walks alongside of the machine. This has led to many stretches of pavement in which the crown has been removed too quickly or else not quickly enough resulting in an uneven stretch of road and an unworkmanlike job. As the pavement goes from thecurve back into a straight stretch, the reverse procedure is necessary, namely, the gradual putting of the crown back into the road.

Accordingly, it is an object of this invention to provide a road finishing machine wherein the crown is automatically adjustable.

Another object of the invention is to provide a road finishing machine wherein the crown is automatically adjustable depending upon the distance traveled by the road finishing machine.

Another object of the invention is to provide the screed of a road finishing machine with first and second crown forming members whose inner ends lie closely adjacent each other and which ends are guided in a crown forming movement whereby paving material is prevented from getting between the inner adjacent ends.

Another object of the invention is to provide a new and novel means of mounting first and second crown forming members of a screed whereby the crown jointing members may be moved angularly with respect to each other while still maintaining the inner ends of the crown forming members closely adjacent each other.

Another object of the invention is to provide -a road finishing machine having a screed mounted thereby with a means for moving the screed relative to the support structure of the machine and also providing a means for adjusting the crown of the screed which means is dependent upon the relative movement of the screed with respect to the support structure of the road finishing machine and the longitudinal travel of the finishing machine.

Other objects and a fuller understanding of this inven- 2 tion may be had by referring to the following description and claims, taken in conjunction with. the accompanying drawings, in which:

FIGURE -1 is a perspective view of a road finishing machine having a screed embodying the principles of the present invention and mounted for movement upon laterally spaced road forms;

FIGURE 2 is a tront elevational view of the machine shown in FIGURE 1;

FIGURE 3 is an enlarged fragmentary view partially in section taken generally along the line 3-3 of FIG- URE 2;

FIGURE 4 is an enlarged tragmentary view in section taken along the line 4 -4 of FIGURE 3 with the exception the crown forming members are shown in a lowered position;

FIGURE 5 is a view taken along the line 5-5 of FIG- URE 4;

FIGURE 6 is a view taken along the line 6-6 of FIG- URE 4;

FIGURE 7 is a view taken along the line 7-7 of FIG- URE 4;

FIGURE 8 is a view taken along the line 8-8 of FIG- URE 6 with the exception that the crown forming members are in a raised position as seen. in FIGURE 2;

FIGURE 9 is a view taken along the line 9-9 of FIG- URE 6; and

FIGURE 10 is a view taken along the line 10-10 of FIGURE 4.

The road finishing machine of the present invention is indicated generally by the reference numeral 15 and includes generally a frame structure '16 having first and second pairs of wheels (17 and 18, respectively, adapted to travel on laterally spaced

road forms

20 and 21. It should be readily recognized that the main frame structure may assume many forms without departing from the teachings of the present invention. Motive power means 24 in form of an internal combustion engine is mounted by the frame structure 16 and is operatively connected to the wheels by suitable means (not shown) to cause the finishing machine to travel on the

spaced road forms

20 and 21. Although only two road forms have been shown in FIGURE 1, it will be readily understood that a plurality of such forms are utilized to form any given length of roadway and these forms not only serve to support and provide travel for the road machine, but serve to contain material from which the road is to he formed, for example, concrete, when such material is in a fluid state and before it has hardened or set up. Various controls have been shown on the road finishing machine 15 as seen in FIGURE 1. These controls are not particularly pertinent from the standpoint of describing the present invention and therefore no further reference will be had thereto. I

A screed 28 is mounted by'the frame structure 16 and, as seen in FIGURE 1, extends transversely to the extent of the

road forms

20 and 21. Only one screed has been shown but, of course, a plurality might be mounted by the frame structure. The screed 28 has first and

second end portions

29 and 30, respectively, which are adapted to reside on the spaced

road forms

20 and 21, respectively. Means are provided which includes a crank arm 33 to operatively connect the screed 28 to the motive power means 24 to reciprocate the screed in a direction generally transverse to the road forms. This means has not been shown in detail since any suitable means will sufliee so long as the screed is reciprocated back and forth in the above described transverse direction. In most machines the transverse movement of the screed is tied in to the longitudinal travel of the machine on the road forms. For example, the machine might be to move at 10, 14 or 20 feet per minute along the forms and with appropriate gearing the screed might be reciprocated at 24, 32 or 40 cycles at any of the above longi' tudinal rates of speed. The linear speed of a machine may usually also be changed by throttle instead of by changing gears and the machine is usually designed to automatically synchronize the screed speed with the linear rate of speed. Since the reciprocal screed speed and the linear speed bear a direct relationship to each other, it may be said that if any means is dependent on one of these it is also dependent on the other in most cases. To aid in mounting the screed 28 to the frame structure and to guide the screed in its reciprocating travel, brackets 35 have been provided on the frame structure on either side thereof which brackets support rollers 36 (FIGURES 3, 5 and 6). Secured t the first and

second end portions

29 and 30 of the screed are straps 39 which, in effect, surround the rollers 36 which in combination support and guide the movement of the screed relative to the frame structure. The rollers travel on plates 38 secured to either end of the screed. It is desirable that the screed be lifted from the road material which it engages, at times, and to accomplish this end, a lifting mechanism 40 has been provided. This lifting mechanism 40 includes a rotatable bar 42 mounted by brackets 43. At either end of the rotatable bar are provided arms 44 which are in turn connected to links 45 suitably secured to the screed 28 as by the roller 46 and member 47 (FIGURE 4) so that the screed may move relative to the lifting mechanism 40 when in operation yet will still be connected when it is desired to lift the screed from the road forms. The lifting mechanism 40 is suitably linked to the motive power means 24 by means, not specifically shown, and upon suitable actuation and subsequent rotation of the bar 42, the screed 28 is lifted from the road forms 20 and 21. This lifting, as mentioned hereinabove, is desirable when the screed is not in use or when it is desired to move the road finishing machine over a given distance at a higher than working speed.

The screed 28 includes a frame 48 which extends the entire distance between the laterally spaced road forms and first and second channel shaped and angularly movable

crown forming members

49 and 50, respectively, which members are engageable with road material 53 which is contained between the spaced road forms. The frame 48 is fixed relative to

members

49 and 50. As will be seen in the drawings, the

crown forming members

49 and 50 each extend substantially half the distance between the road forms. The inner ends of the crown forming members are closely adjacent each other. The frame 48 is supported and secured at either end by means of sections 52 and is generally of open construction across the top portion thereof. The screed frame 48 comprises front and

back members

54 and 55, respectively, which extend in generally spaced parallel, vertical planes. Secured to the front member 54 of the screed frame, at either end portion thereof, are angular plates 56 designed to keep the road material 53 between the road forms 20 and 21. Secured to the plate 56 are slide plates -7 designed to slide on the road forms 20 and 21 and to take most of the wear of the screed. Each of the

crown forming members

49 and 50 comprise first and second side members or

flanges

58 and 59 fitting inside of and adjacent to the front and

back members

54 and 55, respectively (FIGURES 5 and 6). Each of the

crown forming members

49 and 50, respectively, also comprise a bottom member 61 which extends between and interconnects the first and

second side members

58 and 59, respectively. This bottom member 61 is the member which engages and forms the driving surface of the finished roadway. The angular relationship of the bottom members 61 with respect to each other determines the crown of the road. The crown of the finished roadway has been designated by the reference numeral 63 in FIGURE 2 and, as will he noted, if both members 61 lie in a perfectly horizontal plane, then the road will have zero crown which is the crown of a road on a curve and when the members 61 are displaced angula-rly with respect to each other, as shown in FIGURE 2, or the dot-dash line position 62 of FIG- URE 4, then the road may be said to have a positive crown.

The first and

seoondcrown forming members

49 and 50, respectively, are connected to the frame 48 for movement with respect thereto. This movement, as has been hereinabove described, is for the sake of providing the finished road with a crown. It is necessary, however, that the inner ends of the

crown forming members

49 and 50 remain closely adjacent each other so that a smooth road surface results and also so that concrete or other road material will not be allowed to come between the two members. To accomplish this end the

crown members

49 and 50 have been connected. to the frame 48 in a novel manner. Each of the first and

second side members

58 and 59, respectively, have been provided at their outer end portions or in other words the portions which are near the laterally spaced

road forms

20 and 21, respectively, with horizontal guide rollers 64. This is best seen in FIGURES '4 and 10. Each of the front and

back members

54 and 55, respectively, are provided at opposite end portions with a generally horizontal guideway 65 into which the respective horizontal guide rollers 64 reside. In other words, the

crown forming members

49 and 50 are secured to the fixed frame 48 at the outer ends by a sliding pivotconnection. Each of the first and

second side members

58 and 59, respectively, have been provided at their inner end portions with vertical guide rollers 68, and each of; the'front and back

members

54 and 55 have been pro-f vided at an intermediate portion thereof which portion is adjacent the inner portions of the first and

second members

58 and 59 with a member 60 which is provided with substantially vertical guideways 69 and into which the respective vertical guide rollers reside. This means of mounting the

crown forming members

49 and 50 insures; the path which they will follow in adjusting the screedi for a road crown. A yoke member 72 is the bottom members 61 by sliding pivot means 74. A crown control mechanism indicated generally at 76 and seen best in FIGURES 3 through 7, is mounted on the screed frame 48 above the yoke 72 and the inner end portions 73 of the bottom members 61. The crown control mechanism 76 comprises first and second intermeshed gears 80 and -81, respectively, and the first gear 89 is mounted for rotation about a fixed shaft 84. The fixed shaft 84 extends from a housing 112 which is included in the crown control mechanism 76. A rachet wheel 87 is mounted for rotation about the fixed shaft 84 below the first gear 80. The rachet wheel and the first gear 80 are suitably secured together, for example, by a pin (not shown) and therefore are disposed to rotate about the fixed shaft together. A pawl carrier 89 is mounted about the fixed shaft 84 on suitable bearing means 90 for rela tive rotative movement about the fixed shaft. A slotted arm 92 is connected to the pawl carrier 89 by bolts 93 and extends toward the frame structure 16 of the road finishing machine. First and

second pawls

95 and 96 are carried by the carrier '89 and are pivotally mounted thereto by pivot means 97 and 98, respectively. First and

second springs

100 and 101 urge the first and

second pawls

95 and 96, respectively into engagement with the rachet wheel 87. Means which includes a turnable arm 103 is provided for alternatively holding the first and second pawls from engagement with the rachet wheel. This is best seen in FIGURE 7. It will be readily apparent that a simple mechanism might be utilized which would hold either one or the other 'of the pawls out of engagement with rachet wheel and which could also be utilized to hold both pawls out of engagement. with the rachet wheel provided (FIGURES 4, 6 and s which is connected to the inner end portions 73 of each of i tively connected to the motive ne ates when the mechanism was not in use. A stationary arm 105 is secured to the frame structure 16 and extends toward the slotted arm 92. The arm 105 is provided with a slot 106. A pin member 108 resides in the slot 106 of the arm 105 and is adjustably secured in position by means of a nut 109. The second gear 81 has a rotatable shaft 110 secured thereto which is journalled in a bearing 111 in housing 112. The rotatable shaft 110 is provided with a portion having threads 113 thereon. The threads on the rotatable shaft are threadably engageable with complementary threads (not shown) on the yoke member 72 and interconnection of these threads on the yoke and shaft and rotation of the shaft in the desired direction causes movement of the crown forming members. The rotatable shaft has a shoulder 115 on the lower end thereof which prevents disengagement of the yoke and rotatable shaft in the event the threads on the shaft become completely disengaged from the threads on the yoke member.

In operation, let it be assumed that the road finishing machine is being operated on a straight stretch of road. Let it also be assumed that a curve is to be encountered. In operating over the straight stretch of road a full crown would be desired and the screed would assume the general position indicated in FIGURE 2. In the curve portion of the road, the crown should be completely removed and as a result, it is desired that the crown be gradually taken out of the road so that its removal will be practically imperceptible. To accomplish this end the arm 103 (FIGURE 7) is moved to the position shown, to disengage the pawl 95 and allow the pawl 96 to engage the rachet wheel 87. The crank arm 33 which is operapower means 24 is, of course, driving the screed 28 back and forth in its reciprocal travel. Since the screed moves back and forth, the

3 crown control mechanism 76 which includes the pawl carrier 89 must move with it. The arm 105 is mounted to j the frame structure 16 and therefore remains, along with the pin member 108, in a relatively stationary position.

Viewing FIGURES 3'and 7, when the screed and the crown control mechanism moves to the left to the dotdash position 116 of FIGURE 3, then the carrier 89 moves in a clockwise direction relative to the rachet wheel 87. When the screed and the mechanism 76 move back to the right to the full line position, the carrier 89 moves counterclockwise with respect to the rachet wheel. In the clockwise direction of movement, the pawl 96 rides over the teeth of the rachet wheel and in the counterclockwise direction of movement of the carrier 89, the pawl 96 engages in a tooth of the rachet wheel and causes the rachet wheel to move in a clockwise direction. Since the first gear and the ratchet wheel are secured together for rotative movement, then the first gear 80 must also move in a clockwise direction. This drives the second gear 81 in a counterclockwise direction. counterclockwise rotation of the gear 81 and the rotatable shaft 110 causes the threads 113 to, in effect, become unscrewed from the female threads of the yoke 72 to assume the position of FIGURE 6. Movement of the yoke 72 causes the inner end portion 73 of the bottom members 61 and the inner end portion of the

crown forming members

49 and 50 to travel downwardly to remove the crown from the road. In the event that a workman fails to disengage the crown control mechanism when the crown has been removed from the road no harm will be done since the threads 113 on the rotatable shaft 110 only extend for a predetermined distance which distance is just enough for the bottom members 61 to form a straight angle or, in other words, extend in a horizontal plane.

After the curve has been negotiated and it is desired that the crown be returned to the road, the arm 103 is actuated to remove the pawl 96 from engagement with the rachet wheel and to engage the pawl 95 with the rachet wheel. This, in turn, causes the second gear 81 to rotate in a clockwise direction which, in turn, causes the threads 113 on the shaft 110 to re-engage with the threads of the 6 yoke and causes the yoke to be moved to the position shown in FIGURE 8. This causes the inner ends of the

crown forming members

49 and 50 to be lifted or moved upwardly to assume the position shown in FIGURES 2 and 8. Re-engagement of the male and female threads is assured since the concrete is exerting a force in an upward direction to cause the threads to engage each other. The gears and 81 may be easily removed and substituted with gears of different characteristics to regulate the raising and lowering of the crown forming members.

It will thus be seen that a road finishing machine has been provided wherein the crown is automatically adjusted depending upon the distance traveled by the road finishing machine since, this is related to the transverse travel of the screed relative to the machine. In all cases, of course, as shown by the instant structure, the crown is automatically adjusted depending upon the transverse travel of the screed relative to the frame structure. The mounting of the crown forming members, as herein disclosed, insures that these members will travel in a fixed path which insures that the inner ends of these members will travel closely adjacent each other which will in turn prevent paving material from entering the inner confines of the screed.

Although this invention has been described in its pre ferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

What is claimed is:

1. A road finishing machine including a carriage structure having first and second pairs of wheels adapted to travel on laterally spaced road forms, motive power means mounted by said carriage structure and operatively connected to said wheels to cause said finishing machine to travel on said laterally spaced road forms, a screed mounted by said carriage structure and extending transversely to said road forms, said screed having first and second end portions adapted to respectively reside on said spaced road forms, means operatively connecting said screed to said motive power means to reciprocate said screed in a direction transverse to said road forms, said screed including a frame and first and second angularly movable crown forming members engageable with road material contained between said laterally spaced forms, said screed frame comprising front and back members and each said crown forming member comprising first and second side members fitting inside of and adjacent to said front and back members respectively, each said crown forming member comprising a bottom member interconnecting said first and second side members, each said first and second side member having at its outer end portion a first guide roller, each said front and back member having at opposite end portions a first guideway into which said first guide rollers respectively reside, each said first and second side member having at its inner end portion a second guide roller, each said front and back member having at an intermediate portion second guideways into which said second guide rollers respectively reside, a yoke member, sliding pivot means interconnecting said yoke member to the inner end portions of said bottom members, a crown control mechanism mounted on said screed frame above said yoke member, said mechanism comprising first and second intermeshed gears, said first gear mounted for rotation about a fixed shaft, a rachet wheel mounted for rotation about said fixed shaft with said first gear, a pawl carrier mounted about said fixed shaft for angular movement thereabout, a slotted arm connected to said pawl carrier and extending therefrom, first and second pawls pivotally carried by said pawl carrier, first and second springs urging said first and second pawls respectively into engagement with said rachet wheel, means for alternatively holding said first and second pawls from engagement with said ratchet wheel, a stationary arm extending from said carriage structure, a pin member extending vertically from said stationary arm and residing in the slot in said slotted arm, means for adjusting the position of said pin member, said second gear having a rotatable shaft secured thereto and journalled in a bearing, said rotatable shaft having a lower portion with threads thereon, said threads on said rotatable shaft being threadably engageable with complementary threads on said yoke whereby rotation of said rotatable shaft causes angular movement of said crown forming members, and said rotatable shaft having a shoulder thereon preventing disengagement of said yoke and said rotatable shaft.

2. A road finishing machine including a carriage structure having wheels adapted to travel on laterally spaced road forms, motive power means operatively connected to said wheels to cause said finishing machine to travel on said laterally spaced road forms, a screed mounted by said carriage structure, means for reciprocating said screed, said screed including a screed frame and first and second angularly movable crown forming members engageable with road material contained between said laterally spaced forms, said screed frame comprising front and back members and each said crown forming member comprising first and second side members fitting inside of and adjacent to said front and back members respectively, each said crown forming member comprising a bottom member interconnecting said first and second side members, outer guide and guideway means pivotally mounting the outer end portions of said crown forming members to said screed frame, inner guide and guideway means mounting the inner end portions of said crown forming members to said screed frame, a yoke member, sliding pivot means interconnecting said yoke member to the inner end portions of said bottom members, first and second intermeshed gears carried by said screed, a rachet wheel mounted for rotation in unison with said first gear, a pawl carrier mounted for angular movement with respect to said rachet wheel, a slotted arm extending from said pawl carrier, pawl means carried by said pawl carrier, spring means urging said pawl means into engagement with said rachet wheel, means for selectively holding said pawl means from engagement with said rachet wheel, a stationary arm extending from said carriage structure, a pin member extending vertically from said stationary arm and residing in the slot in said slotted arm, said second gear having a rotatable shaft secured thereto and journalled in a bearing, said rotatable shaft having a lower portion with threads thereon, said threads on said rotatable shaft being threadably engageable with complementary threads of said yoke.

3. A road finishing machine including a carriage structure having wheels adapted to travel on spaced road forms, motive power means mounted on said carriage structure and operatively connected to said wheels to cause said finishing machine to travel on said spaced road forms, a screed mounted by said carriage structure and extending transversely to said road forms, means operatively connected to said screed to reciprocate said screed in a direction transverse to said road forms, said screed including a frame and first and second movable crown forming members adapted to engage road material contained between said spaced forms, means mounting said first and second crown members to said frame for angular movement with respect to each other, a yoke member, sliding pivot means interconnecting said yoke member to the inner end portions of said bottom members, a ratchet wheel mounted for rotation on said screed, a pawl carrier mounted for angular movement with respect to said ratchet wheel, pawl means pivotally carried by said pawl carrier, means urging said pawl means into engagement with said ratchet wheel, sliding pivot means interconnecting said pawl carrier and said carriage structure, and means interconnecting said ratchet wheel and said yoke member whereby movement of said ratchet wheel causes movement of said yoke member.

4. A road finishing machine including a carriage structure having first and second pairs of wheels adapted to travel on laterally spaced road forms, motive power means mounted on said carriage structure and operatively connected to said wheels to cause said finishing machine to travel on said laterally spaced road forms, a screed mounted by said carriage structure and extending transversely to said road forms, said screed having first and second end portions adapted to respectively reside on said spaced road forms, means operatively connecting said screed to said motive power means to reciprocate said screed in a direction transverse to said road forms, said screed including a frame and first and second angularly adjustable crown forming members engageable with road material contained between said laterally spaced forms, said crown forming members determining the form of the road surface, means actuated by the reciprooable movement of said screed for automtically adjusting the angular relationship between said crown forming members, said means including a yoke member connected to the inner ends of said crown forming members, a crown control mechanism mounted on said screed frame above said yoke member, said mechanism comprising first and second intermeshed gears, said first gear mounted for rotation about a fixed shaft, a ratchet wheel mounted for rotation about said fixed shaft with said first gear, a pawl carrier mounted about said fixed shaft for angular movement thereabout, a slotted arm connected to said pawl carrier and extending toward said carriage structure, first and second pawls pivotally carried by said pawl carrier,

first and second springs urging said first and second pawls respectively into engagement with said ratchet wheel, means for alternatively holding said first and second pawls from engagement with said rachet wheel, a stationary arm extending from said carriage structure, a pin member extending vertically from said stationary arm and residing in the slot in said slotted arm, said second gear having a rotatable shaft secured thereto and journalled in a bearing, said rotatable shaft having a lower end portion with threads thereon, said threads on said rotatable shaft threabaly engaging complementary threads on said yoke whereby rotation of said rotatable shaft causes vertical movement of said crown forming members 5. A road finishing machine including a carriage structure having wheels adapted to travel on laterally spaced road forms, motive power means mounted on said carriage structure and operatively connected to said wheels to cause said finishing machine to travel on said laterally spaced road forms, a screed mounted by said carriage structure, means operatively connecting said screed to said motive power means to reciprocate said screed, said screed including a frame and first and second angularly movable crown forming members engageable with road material adapted to be contained between said laterally spaced forms, said crown forming members determining the surface contour of the road, a yoke member interconnecting the inner ends of said crown forming members, first and second intermeshed gears carried by said frame, said first gear mounted for rotation about a fixed shaft, a rachet wheel mounted for rotation about said fixed shaft with said first gear, a pawl carrier mounted about said fixed shaft for angular movement thereabout, first and second pawls pivotally carried by said pawl carrier, first and second springs urging said first and second pawls respectively into engagement with said rachet wheel, means for selectively maintaining said first and second pawls from engagement with said ratchet wheel, an arm member extending from said pawl carrier to said carriage, a stationary member on said carriage slidably interconnected to said arm member for causing the angular movement of said pawl carrier about said fixed shaft, said second gear having a rotatable shaft secured thereto and journalled in a bearing, said rotatable shaft having a lower end portion with threads thereon, and said threads on said rotatable shaft threadably engaging complementary threads on said yoke whereby rotation of said rotatable shaft causes vertical movement of said crown forming members.

6. A road finishing machine including a carriage structure having wheels adapted to travel on laterally spaced road forms, motive power means mounted on said carriage structure and operatively connected to said wheels to cause said finishing machine to travel on said laterally spaced road forms, a screed mounted by said carriage structure and extending transversely to said road forms, means operatively connecting said screed to said motive power means to reciprocate said screed in a direction transverse to said road forms, said screed including a frame and first and second angularly movable crown forming members engageahle with road material adapted to be contained between said laterally spaced forms, raising and lowering means interconnecting said crown forming members, a ratchet wheel mounted for rotation on said frame, a pawl carrier mounted for angular movement with respect to said ratchet wheel, pawl means pivotally carried by said pawl carrier, means urging said pawl means into engagement with said rachet wheel, an arm member extending from said pawl carrier to said carriage, a stationary member on said carriage slidably interconnected to said arm member for causing the angular movement of said pawl carrier relative to said ratchet wheel and means operatively interconnecting said rachet Wheel and said raising and lowering means whereby rotation of said rachet wheel causes movement of said crown forming members.

7. A road finishing machine including a carriage structure adapted to travel on spaced road forms between which road material is adapted to be contained, a screed operatively connected to said carriage structure and adapted to extend in a transverse direction between said road forms, first drive means for reciprocally moving said screed in said transverse direction, said screed including first and second crown forming members having inner adjacent end portions, raising and lowering means connected to said inner adjacent end portions of said first and second crown forming members, and second drive means mounted on said screed for actuating said raising and lowering means, and means interengaging said second drive means and said carriage structure to power said second drive means in response to the reciprocal movement of said screed relative to said carriage.

8. A road finishing machine including a carriage structure adapted to travel on spaced road forms between which road material is adapted to be contained, a screed operatively connected to said carriage structure and adapted to extend in a transverse direction between said road forms, first drive means for reciprocally moving said screed in said transverse direction, said screed including crown member means for engaging road material, raising and lowering means connected to said crown member means at an intermediate portion thereof, and second drive means mounted on said screed for actuating said raising and lowering means, and means intereng-aging said second drive means and said carriage structure to power said second drive means in response to the reciprocal movement of said screed relative to said carriage.

References Cited in the file of this patent UNITED STATES PATENTS 1,265,499 Parrish May 7, 19.18 1,741,459 Heltzel Dec. 31, 1929 2,150,618 Blackwell Mar. 14, 1939 2,299,700 Millikin Oct. 20, 1942 2,351,593 Barber June 20, 1944- 2,358,085 Sept. 12, 1944 2,449,710 Miller et a1 Sept. 21, 1948