Showing papers on "Screed published in 1994"

Paver with material supply and mat grade and slope quality control apparatus and method

Abstract: An asphalt paver includes a microprocessor controlled integrated control system to control both the operation of a tractor unit of the paver and the positioning of the screed during a paving operation. A paver operator may operate the paver and monitor the screed position with respect to a grade reference. The correction of grade or transverse slope errors is accomplished by monitoring the linear advance of the paver and then measuring a any deviation of the screed with respect to a grade reference. The amount of vertical deviation and the linear advance since a most recent correct reading allows a rate of deviation per unit advance of the paver to be determined. A correction is applied as a change in the angle of attack of the screed, the change being equal and opposite to the determined rate of deviation. A transverse slope change is also measured directly at the screed. A measured transverse angular deviation is translated into a vertical deviation which is then translated into a rate of deviation per unit advance of the paver with a corrective twist being applied to the screen to offset the deviation. Advantageously dual grade sensors and dual slope sensors are contemplated to provide an automated microprocessor controlled grade and slope control in accordance herewith.

Control device for asphalt finisher

Abstract: Efficient paving operation requires that the levelling operation of asphalt be carried out accurately along a reference line (A) which follows a given direction along a roadside. A simple and effective automatic control device for controlling the steering direction in conjunction with adjustments of the screed (6) for an asphalt finisher (1) (shortened to finisher) is presented. The control device automatically regulates the extension or contraction of the screeds (6) on both sides of the finisher (1) in reference to a visual display of the reference line (A) following some objects along the roadside. The visual detection system of control is simple and economical and provides an accurate control over the direction of paving.

Paving machine with drop-then-stop dowel bar insertion

Abstract: A paving machine having a medially located dowel bar feeder positioned in front of a dowel bar inserter. The machine has a screw or paddle for spreading the concrete and a front strike-off to allocate a proper amount of unconsolidated concrete beneath the machine. Next in line, internal vibrators are mounted to the machine to perform a preliminary consolidation of the concrete, followed by a screed to meter out a correct volume of consolidated concrete for a finished concrete slab. To the rear of the screed, the dowel bar feeder drops dowel bars in a predetermined pattern on the top surface of the consolidated concrete. The dowel bar inserted is mounted to the paving machine behind the dowel bar feeder and includes a plurality of vibrating forks which descend to engage the dropped dowel bars and insert the dowels into the unhardened concrete. In operation, the dowel bars are dropped and the paving machine is driven forward until the forks are over the dropped dowel bars. The paving machine is then stopped and the forks are lowered to insert the dowel bars into the concrete. A finishing machine is operated behind the paving machine to insert center bars and to produce a final consolidated and smoothed grade in the concrete. The paving machine may be adapted to insert dowel bars for transverse joints in a straight or a skewed pattern. In the case of the straight pattern, all the dowel bars for each transverse joint are dropped at the same time. For the skewed pattern, the dowel bars for each transverse joint are dropped one at a time.

Paving machine with gravity feed hopper and auger mechanism

Abstract: A paving machine has a gravity feed hopper which is capable of delivering by gravity to the paving apparatus substantially all of the paving materials stored in the hopper without employing any internal conveyors. The discharge opening of the hopper is selectively closed by a feeder gate, the degree of opening of which is preferably coordinated with other operating parameters of the machine such as vehicle speed, distributing auger height and/or speed, and screed operation. Use of the gravity feed hopper significantly reduces construction and maintenance costs, provides a more uniform feed of materials from the hopper, and permits the use of a smaller engine. The paving machine as thus constructed is also relatively easy to operate and thus can be controlled by a single operator seated in the vicinity of the screed.

Powered rotary screed

Abstract: A powered rotary screed has a plurality of interchangeable modules of different lengths so that the power screed can accommodate a range of job applications. Additionally, the rotary screed comprises a centrally located expansion member that can be adjusted to cause an upper ridge member of the rotary screed to expand outward, thus raising a medial portion of the roller screeds so that they may be adjusted to maintain horizontal alignment. The screed is propelled by two drive tubes that are supported by drive modules and powered by hydraulic motors. The screed further comprises a two-section strike tube which is likewise powered by a hydraulic motor. An operator rides in an operator's station and controls the speed and direction of the rotary screed.

Manual concrete screed handle

Abstract: A releasable screed handle for being operatively secured to a selected screeding member to manipulate the screeding member through the various spreading and smoothing motions requisite in working concrete. The screed handle consists of an elongated handle that is pivotally affixed, at an angle of about 105° from the vertical, to a lockable clamping plier that is capable of receiving and clamping a screed member of selected size and thickness.

Screed assembly for an asphalt paving machine

Abstract: A screed assembly (10) has a screed plate (22) that is formed of a material having a thermal conductivity of less than about 25 W/mK, and a thermal barrier material (32) having a thermal conductivity of less than about 0.5 W/mK that substantially covers an upper surface (36) of the screed plate (22). The low thermal conductance properties of the screed plate (22) obviate the need for auxiliary heating systems to preheat or maintain the screed plate (22) in thermal equilibrium with a paving material (31).

Vibratory screed for a road finisher

Abstract: The invention relates to a vibratory packing plank for a road finisher, having a vibration unit, which comprises a vibration element exhibiting a large-area base plate and coupled to a vibration drive, and a guide plate positioned obliquely towards the base plate, a vibration strip being disposed between the guide plate and the base plate of the vibration unit, which vibration strip is coupled to the vibration drive and provided with a run-in slope.

Concrete road surface grader

Abstract: The utility model relates to a concrete road surface grader for a highway, which is provided with a supporting frame and two foot frames for side wheels, a screed is arranged between the two foot frames for side wheels, and simultaneously, a drive mechanism which can make the screed move from left to right is arranged on the supporting frame. The utility model has simple structure and has the advantages of realizing mechanization control and continuous work, reducing construction strength of workers and raising work efficiency.

Automatic controller of asphalt finisher

Abstract: PURPOSE:To simplify the structure, by reducing the number of detectors. CONSTITUTION:Detectors 14, 15 like a CCD camera detecting a basic line A on a road D are equipped at the sides of a screed 6. The detectors 14, 15 are electrically connected to a controller 23. The driving device and the extension device 8 of screed are regulated by the controller 23 in accordance with the detected result of the basic line by means of the detectors 14, 15. Since the detectors 14, 15 are commonly used for the driving device and the extension device 8 of screed, the required number thereof is reduced.

Winch construction for a vibratory concrete screed

Abstract: A winch assembly is connected to each end of a vibratory concrete screed to move the screed across a concrete slab to be finished. Each winch assembly includes a rotatable drum with a cable wound on the drum. The free end of each cable is connected to a fixed object mounted along the side of the concrete slab. To wind the cable on the drum and move the screed along the slab, the eccentric drive shaft of the screed is connected through a variable speed belt drive to the respective drum. Each belt drive includes an adjusting mechanism for varying the effective diameter of a belt drive pulley, thus providing a variation in speed. Each winch assembly also includes an eccentric gear speed reducing mechanism, which is connected between the belt drive and the drum to further reduce the output speed to the cable drum.

Extension controller of screed in asphalt finisher

Abstract: PURPOSE:To control a screed to smoothly follow along a basic line CONSTITUTION:A couple of front and rear detectors 14, 15 checking a basic line A, are equipped at the outside ends or a screed 6 which is extensible by a screed extension device 8 A controller 23 judges whether the width of a roadface R is varied, widened or narrowed, from the signals of the detectors 14, 15 and chooses the rear detector 15 when the width is equal or wider and chooses the front detector 14 when it is narrower to follow the width In both cases when the road width is widened or narrowed, the ends of screed 6 do not extend the outside of basic line A

Utilisation of the reinforced-concrete floors of houses as a heat-storage means for the economical operation of heating systems

Abstract: Technical problem of the invention The method used hitherto for structural heat insulation of intermediate floors made provision for heat insulation of 6-8 cm. In the case of a floor heating system, the heat-storage volume was restricted to the approximately 40-mm-thick screed layer. In order to make use of the off-peak power tariffs and for cost-effective usage of energy, the entire reinforced-concrete slab, including the screed, is used as heat-storage means. The storage volume permits the peak power tariff range to be bypassed without requiring a recharging time. Solution of the technical object The integration of the complete reinforced-concrete floor of the basement level or of the ground level as heat-storage means of the house is achieved by changing the heat-insulating system. The heat-insulated contour of the house is shifted outwards in an encapsulated state. Application area The application area is constituted by boiler-type floor heating systems with electric heating and an electrical direct heating system for the floor and alternatively the ceiling. The advantages lie in the exclusive use of the inexpensive off-peak power available.

Application of polymer overlays to concrete and steel bridge decks

Abstract: This paper discusses the development and properties of the Bridgemaster polymer overlay system, based on acrylic resins, which combines the waterproofing and wearing course functions in one surface. Bridgemaster has long-life, is cost-effective, and requires little maintenance. Its basic elements are: (1) a primer that must be applied to the substrate to improve adhesion; (2) a polymer screed, which blends inorganic fillers with a special low viscosity acrylic copolymer developed; (3) an aggregate, scattered over the system to provide non-slip characteristics; and (4) a reactive acrylic sealer, applied to enhance aggregate retention. Bridgemaster can be applied all the year round in ambient temperatures between -10 and 40 degrees Celsius. It has been used on many structures in the UK and overseas. Two UK cases are presented, to illustrate Bridgemaster's application to bridges. The Cawood Swing Bridge across the River Ouse has four fixed spans and a swing span, each with a steel deck. There is no evidence of damage wear to the surface laid in 1989. The Menai Suspension Bridge between Anglesey and mainland Wales has reinforced concrete slabs laid on a steel deck; Bridgemaster was applied in mid- 1994 to the client's full satisfaction. For the covering abstract see IRRD 869077.

Pressing method of paving material end part and device thereof

Abstract: PURPOSE:To dispense with any manual operation by the use of a rake and the like so as to eliminate various problems by the use of a rake and the like, when the end part of a paving material is pressed. CONSTITUTION:The end part of a paving material 18 made of asphalt mixture 8 levelingly laid and compacted is obliquely pressed by means of a pressing device 19 behind a screed 13. Namely, the end part of the paving material 18 on the joint part between the end part of existing pavement or a structure on a roadbed and newly scatteredly provided paving material 18 on the roadbed is brought in contact with the taper face part 20 of a pressing member 21, and the underside of the pressing member 21 is brought in contact with the upper face of end part of the existing pavement 37 or the structure. The end part of the paving material 18 is obliquely pressed by means of the taper face part 20, by moving the pressing member 21 along the extending directio of the end part while rotating the pressing member 21 by a hydraulic motor 32.

Extensible riugh finishing screed

Abstract: PURPOSE: To eliminate a mechanical problem, which damages the operability of a screed, by improving the support of the rough finishing element of the extensible rough finishing screed especially for a road finishing machine. CONSTITUTION: This extensible finishing screed V is provided with two extensible members A, B supported on a towed central part M in order to displace in a horizontal direction with respect to the traveling direction of this. Supporters W1 and W2 are respectively fixed to these extensible members and a plurality of rough finishing elements 15 are arranged at the respective supporters. These rough finishing elements periodically apply projecting power pulses in a vertical direction to the ground G by a projecting power drive 14. The upward reaction force of the power pulse is supported by mass, which is remarkably larger than the mass of the rough finishing elements to be installed over the projecting power drive. The two members A, B are arranged to be front and back in the towing direction of them so that the elements 15 of these members may be overlapped in a horizontal direction with respect to the towing direction 1 of the part M without having these elements.

Heat passing tunnel of screed burner

Abstract: PURPOSE: To efficiently apply a heat to a pavement screed before operation of a paving machine. CONSTITUTION: Related to a heating device for heating a substantially planer screed plate 24 for a paving machine comprising a plate being spaced from the screed plate, with a space being defined therebetween, a heated gas is fed into a tunnel 36 wherein a heated gas inlet is connected to the space. At least some of the heated gas is directed from the tunnel substantially parallel to the screed plate. The tunnel is formed from a plurality of tunnel branches 40 and 42, with orifices 44 and 46 which determine the direction where the heated gas will be directed attached to the end of each tunnel.