GB561962A - Improvements in or relating to paving - Google Patents

Abstract

561,962. Paving roads. BLAW-KNOX CO. Jan. 14, 1942, No. 558. Convention date, Sept. 23, 1941. [Class 107] A concrete paving machine comprises a car movable about the area to be paved and carrying a spreader movable to and fro across said area, a transverse strike-off with a narrow bottom edge which strikes off the upper surface of the concrete and pushes the larger projecting aggregates forward to leave fissures in the concrete, and an elongated high-frequency tamper substantially parallel to the said strike-off and spaced behind same a distance greater than the thickness of the concrete and causing said fissures to be closed from the bottom up by movements within the interior of the concrete. A main frame 2, with wheels 3 running on rails 5, has transverse tracks 7, 8, supporting a carriage 9 carrying a concrete, &c. spreading and advancing means 14 adapted, at the end of each traverse, to be rotated to the opposite side of the concrete, &c. pile as in Specifications 546,193 and 552,226. Behind the spreader, &c. 14 is a transverse narrowedged screed or strike-off 36 adapted to level the concrete, &c. and having at its ends forwardly extending portions 37 adapted to restrain sideways movement of the concrete, &c. ; the screed is connected to pivoted links 38, 39, and may be raised and lowered as in Specification 546,193 or by a hydraulic jack 49 acting through crank 46, shaft 42 and arms 43 connected by adjustable links 44 to the links 38, indicating means 50, 51, being provided. Spaced behind the screed, by a distance substantially greater than the thickness of the concrete, is a vibratory or conditioning unit C comprising a tamper 54 which may be continuous but is preferably centrally divided, as shown into parts 54a, 54b, each comprising a channel 56 carrying a U-beam 55 with a jacket 57, the outer end of the U-beam being tapered as at 55a Fig. 7, and having a separate removable jacket 59, whereby the effective length of the tamper may be varied. The ends of the tamper sections are supported by leaf springs 60, 61, suspended by links 62 from cranks 71, 65, connected by a link 72 and operated through a hydraulic jack 79 and shaft 63 to raise and lower the tamper units ; the cranks 65 connected to the inner ends of the tamper sections are carried by a tube 68 surrounding the shaft 63 and adapted to be adjusted relative thereto by arms 63<1>, 73, Fig. 11, and screw-and-nut gearing 74, 75, locked by a chain 78 after adjustment, whereby the inner ends of the tamper units may be further raised or lowered independently of the outer ends. Indicator 82 shows the general position of the tamper units, and indicator 83 shows the relative position of the inner ends thereof. Vibration is effected by a rotating, unbalanced-weight device carried by the tamper units and driven from the engine 31 through belts 88, 86, and universallyjointed shafts 85. Swinging of the links 62 is prevented by diagonal links 91. The hydraulic jacks 49, 79, may be operated by oil circulated by a pump driven by the engine 31. In operation, the screed leaves a pitted and fissured concrete surface, the pits and fissures being closed by the vibrations of the tamper, which also smooths the surface of the concrete.