GB1295159A - - Google Patents

Abstract

1295159 Paving machines BLAW KNOX CONSTRUCTION EQUIPMENT INC 23 Sept 1970 [24 Sept 1969] 45261/70 Heading E1G A road or pavement widening machine comprises a tractor 10 which runs on an existing paved surface 12 and includes apparatus for depositing paving material, e.g. asphalt, rock aggregate, concrete, dirt or hard core, into a course 16 and levelling it to a predetermined level and transverse slope, the levelling being effected by a strike-off blade 46 which extends to the side and rearwardly of the tractor chassis, its inboard end being carried by a vertically adjustable support assembly 48 and its outboard end being adjustable both transversely, to suit the width of the course 16, and in height, the height adjustments of the two ends of the blade being effected continuously and automatically by hydraulic cylinders 64, 80 under control of devices sensitive to variations of height and slope of the blade from a corresponding datum height and slope, respectively. As indicated in Fig. 3, the height datum level is preferably obtained from the grade of the existing pavement by employing a shoe 114 which slides along the existing pavement, the shoe being carried by an arm 106 pivoted to sensor 102 which is adapted to move vertically with the inboard end of the blade. Pivotal movements of the arm 106, on either side of a null position generate electrical impulses in a circuit 116, either by changing a resistance to unbalance a Wheatstone's bridge or by closing the contacts of limit switches, the impulses, suitably amplified, being passed to a solenoid valve 96 to cause operation of the cylinder 80 in one or the other direction such as to restore the null position by raising or lowering the inboard end of the blade 46 and consequently the sensor 102. The slope datum may either be obtained, as indicated in Fig. 3, from a pendulum 136 of a gravity sensor 104 attached to the blade 46, or from a transverse sensing rod (156, Fig. 5, not shown) which extends from the inboard mounting of the blade to a point on the opposite side of the tractor where it carries a shoe (158) sliding on the existing pavement, control of the operation of the cylinder 64 by the sensor 104 or the sensing rod being in either case similar to that for controlling the operation of cylinder 80, i.e. by generating an electrical impulse in a circuit 142 which via solenoid valve 98 operates the cylinder 64 to restore a null position of the sensor or sensing rod. The cylinder 64 is connected diagonally between an upright 60 on the tractor and the inboard section 56 of a telescopic boom 50 which is extensible and retractable by means'of a hydraulic cylinder 62 to vary the lateral spacing between the outboard end of the blade 46 and the tractor. Edger plates 70, 74 are provided, the latter being adjustable to correspond with the angle of the blade 46 as determined by the degree of extension of boom 50. The blade and boom assembly may be mounted alternatively on the opposite side of the tractor, by providing detachable mountings 66, 68. A hopper 18 receives the material to be delivered to the course in advance of the blade 46, a conveyer 38 directing the material laterally via guide plates 42, 44 to the course 16.