US3888542A

US3888542A - Road planing machines

Info

Publication number: US3888542A
Application number: US424723A
Authority: US
Inventors: John Edward Gowler
Original assignee: NON IMPACT SURFACES Ltd
Current assignee: NON IMPACT SURFACES Ltd
Priority date: 1972-12-22
Filing date: 1973-12-14
Publication date: 1975-06-10
Anticipated expiration: 1992-06-10
Also published as: GB1459183A; FR2211563A1; IT1000585B; NL7317336A; AU6371573A; ZA739418B; DE2364028A1; BE808953A

Abstract

The invention consists of apparatus for machining road surfaces of the kind comprising a body having road wheels and carrying a cutting drum mounted for rotation about an axis extending transversely of the direction of travel and movable into contact with a road surface to cut away a layer of the surface in which there is a first hydrostatic pump, connected to a hydrostatic motor for driving the drum in which there is a second hydrostatic pump connected to a hydrostatic motor for driving at least one of the road wheels and in which there is means to drive both of the pumps at constant speed, and both of the pumps have infinitely variable displacements, means being provided for varying the displacements of the pumps individually whereby any combination of drum and road wheel speeds may be provided.

Description

United States Patent 1w:

Gowler 1 June 10, 1975 1 1 ROAD PLANING MACHINES John Edward (iowler, Rcdhill. England 1751 Inventor:

22 Filed: Dec. 14. 1973 1211 Appl. N81424J23 130] Foreign Application Priority Data Dec. 22, 1972 United Kingdom 59513/72 [521 U.S. C1. t. 299/1: 173/24; 299/39 [51 1 Int. Cl. .1 E2lc 47/00 [58l Field of Search 299/39. 14, I; 404/95, 404/77; 60/492; 180/53 CD; 172/123. 3; 173/24 [56 References Cited UNITED STATES PATENTS 2.273154 2/1942 Davis 464/95 X 3,300,000 1/1967 Stoykc 60/492 X 3.414.327 12/1968 Austin i l t r t i 1 t 4 299/39 X 3.617.091 11/1971 Mooney 299/39 1767262 10/1973 Pentith 299/39 X Primary ExaminerErnest R. Purser Assistant E.tuminer-Wi1liam F. Pate. lll

Attorney, Agent. or Firm-Young & Thompson 157] ABSTRACT The invention consists of apparatus for machining road surfaces of the kind comprising a body having road wheels and carrying a cutting drum mounted for rotation about an axis extending transversely of the direction of travel and movable into contact with a road surface to cut away a layer of the surface in which there is a first hydrostatic pump, connected to a hydrostatic motor for driving the drum in which there is a second hydrostatic pump connected to a hydrostatic motor for driving at least one of the road wheels and in which there is means to drive both of the pumps at constant speed, and both of the pumps have infinitely variable displacements. means being provided for varying the displacements of the pumps individually whereby any combination of drum and road wheel speeds may be provided.

10 Claims, 7 Drawing Figures PATENTEDJUH 10 1975 SHEET PATENTED JUN 1 0 I975 SHEET ROM) PLANING MACHINES The invention relates to apparatu for machining road surfaces and prmides apparatus for machining road surfaces of the kind comprising a body having road wheels and carrying a cutting drum mounted for rotation about an axis extending trans\ersel of the direction of travel and movable into contact with a road surface to cut away a layer ol'the surface in which there is a first hydrostatic pump. connected to a hydrostatic motor for driving the drum in which there is a second hydrostatic pump connected to a hydrostatic motor for driving at least one of the road wheels and in which there is means to drive both of the pumps at constant speed, and both of the pumps have infinitely variable displacements. means being provided to vary the displacements of the pumps individually whereby any combination of drum and road wheel speeds may be provided.

Such a machine provides great advantages over the known machines particularly because the control over the operating speeds of the drain and the road wheels is so much greater than in machines having conventional mechanical drives. It has been previously preferred to drive the drum by hydrostatic means but this arrangement does not provide sufficient control over the power and speed of the machine.

It is preferred that there are valve means for connecting the pumps to the motors in a road machining position wherein the first pump is connected to the drum motor and the second pump is connected to the road wheel motor and a transit position wherein the first pump is connected to the road wheels.

It is necessary to provide a relatively large amount of power to drive the drum and a relatively small amount of power to drive the road wheels during machining, while a relatively large amount of power has to be supplied to the road wheels during transit from one place to another. An advantage of the above arrangement is that there is considerable lessening in the size of the second pump as the first pump which may be much larger can be used to drive the road wheels during transit.

Preferably the pumps are swash plate pumps driven by a single engine arranged to be driven at constant speed and the speeds at which the motors are driven is variable by varying the angle of the swash plates.

The hydrostatic motor for the drum may be mounted at least partly within the drum.

Preferably the drum is arranged to be driven by two hydrostatic motors of which the rotors are arranged for rotation about the same axis. the drum being mounted on the two rotors.

In a preferred arrangement there is at least one jockey wheel to control the depth of cut of the drum and there is at least one double acting hydraulic ram to control the position of the jockey wheel and pump means to operate the ram. there being in the hydraulic connection between the pump means and the ram a hydraulic accumulator to absorb shock loads on the jockey wheel.

There may be means to detect the position of the jockey wheel and means to operate the ram in a sense to move the jockey n heel back to a predetermined position if the detection means detects movement of the heel from the said predetermined position.

Preferably the detection means comprises micro switches settable in a position corresponding to a desired cutting depth.

The invention further provides a method of machining a road surface using a machine of the kind comprising a body having road wheels and carrying a cutting assembly having a cutting drum pivoted for rotation about an axis extending transversely of the direction of travel which cutting assembly has means to engage the road surface to limit the depth of cut of the drum in which during cutting the assembly is freely suspended from the machine and the cutting pressure is provided solely by the weight of the cutting assembly.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a side elevation of an apparatus according to this invention;

FIG. 2 is a schematic plan view of parts of the apparatus;

FIG. 3 is a view partly in section showing the arrangement and construction of the cutting drum. the ram being omitted for clarity.

FIG. 4 is an enlarged side elevation of the cutting drum and its associated parts;

FIG. 5 is a section through one rear road wheel showing the driving motor;

FIG. 6 is a diagrammatic drawing of the hydrostatic circuit; and

FIG. 7 is a diagrammatic drawing of the hydraulic circuit for the hydraulic rams for the depth controlling means.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION Referring first to FIGS. 1 and 2 the apparatus comprises a chassis frame It), generally of rolled steel section members suitably reinforced where necessary. The chassis has mounted thereon two rear road wheels II, l2 two single steerable front road wheels 13, 14, an operators cab 15, a diesel engine 16, a burner assembly 18, and a rotatable cutting drum 1'). The two front wheels l3, l4 are steerable from the cab 15 via a mechanism (not shown). If desired window blades may be provided to keep cut material away from the path of the rear wheels.

Each rear wheel is driven by a single hydrostatic motor 21. FIG. 5 shows the wheel I2 and the associated motor 21 which is secured to the chassis by a plate and is partially housed within the wheel hub.

FIGS. 3 and 4 show the cutting drum and its associated mounting arrangement and one of its two driving motors 22. The other motor (not shown) is mounted inside the other end of the drum. Each motor 22 is bolted to an internal radial flange 23 on the drum. The motors are connected to the chassis [0 by a pivoted cradle 40 (FIG. 3) which permits the inclination of the drum axis to be varied from the horizontal for use when planing a eambered road surface. or when cutting away a layer of varying depth.

A beam SI is attached to the chassis l0 and two lugs 52., 53 are attached to the beam SI. A tube 40 is pivotally mounted to the

lugs

52, 53 by two further lugs 54, 55 for rotation about a fore and aft axis. Pivotally mounted at each end of the tube 40 for rotation about a transverse axis in a support member 42. The drum I9 is attached to the members 42 by means of the hydrostatic motors 22, one within each end of the drum. The

member 42. together with the drum I9, may be raised and lowered by a hydraulic ram 43 pivotally connected to the chassis and to a bar 56 extending between the members 42. Connected to the support members 42 are further legs 57, each carrying a roller which is inside the width of the cutting drum. The rollers 45 are adjustable in height relative to the drum by means of hydraulic rams within the legs 57.

One cutting tooth 24 is shown welded to the periphcry of the steel drum 19. There are however a plurality of such teeth arranged across the full width of the drum along a line which, in developed form. has the shape of a chevron or V. so that a single rotation of the drum re moves a layer of road surface having the full width of the drum. The cutting drum of this example has a width of 7 feet 6 inches. The longitudinal axis of the drum is at 90 to the longitudinal axis of the apparatus.

The height of the drum relative to a road surface is variable by adjustment of the two wheels 45, and the drum may be lifted clear of the road surface by means of ram 43.

Each cutting tooth 24 has an H cross-section and has a replaceable carbide tip which can be reground, for example, as shown in U.S. Pat. No. 1,284,539.

The burner assembly I8 includes propane gas heaters 85 and is mounted in front of drum I9 and has the same width as the drum. The assembly has two mounting members 82a movable vertically in slides 82 and the height of the assembly above the road is adjustable by means of a ram and two wires 83, 84 attached to the members 81. The assembly includes a hydraulically driven fan, ducting, controls. pipework and gauges. all not shown.

FIG. 6 shows the main hydrostatic circuit for the machine. Swash-plate pump 62 driven by engine 16 has a displacement variable by a lever 62a. The pump is connected to a reservoir 61. The drum motors 22 are con' nected to the pump circuit by means of valves 64 and 65 and are unidirectional. Each driven motor is provided with a cross line relief valve 66 to relieve pressure if shock loads are produced (e.g., when the drum encounters a harder material) and the main feed lines are provided near the pump with cross line relief valves 63 which control the pressure of the circuit. The pump 62 and circuit may alternatively be connected to the wheel drive motor 21 by way of valves 67, 81.

Swash plate pump 71 has a displacement variable by lever 71a and is fed from a reservoir 70. The pump 7] is less powerful than the pump 62.

The circuit for the pump 71 has two main lines lead ing to a valve 74 having two positions. a first position where the lines are connected to the supply and return lines to the motor 2l and a second position where the two main lines are connected together and the pump 7] is idling.

The main lines are interconnected by cross line relief valves 72 to regulate the pressure in the lines.

From the valve 74 the main line connects to the valve 75.

The motors 21 each have three connecting points A. B and C. In one position of the valve 75 fluid flows into the point A and out of the points B and C. This provides for half displacement ofthe motors giving low torque/- high speed operating condition.

In a second position of the valve 75 fluid is caused to flow into the points A and B and out of point C. This provides for full displacement of the motors giving high torque/low speed operating condition.

Fail safe brake cylinders 77 are provided for the rear wheels I] and I2 and the brakes are released as pressure builds up in the inlet lines leading to the points A or A and B.

A valve 78 is provided to connect together the input and output lines to the motors 21 to allow the vehicle to be towed in the event of a breakdown.

The valves 64, 65. 67. 8] and 74 are all controlled simultaneously by a ram 68 controlled by a valve 69 and supplied by a hydraulic pump 80. The valves move between a planing condition of the machine when the valves 64. 65 connect the drum motors 22 into the circuit of the pump 62. the valves 67. 81 are closed and the valve 74 is in its first position connecting the wheel motors 21 with the circuit of the pump 71'. and a transit position where the valves 67, 81 connect the wheel mo tors 21 into the circuit of the larger pump 62, the valves 64, 65 are closed and the valve 74 is in its second position allowing the pump 7] to free wheel.

The direction of rotation of the road wheels can be reversed by reversing the swash plate angle on the pump which is at that time connected to the road wheel motors 21. The speed of rotation of the drum and of the road wheels is similarly varied by varying the swash plate angles in the pumps while maintaining constant the speed of the engine 16. The hydraulic circuit to the various rams is quite conventional. The only part ofthe circuit which needs explanation is shown in FIG. 7 which shows the circuit to the rams controlling the roller height control wheels 45.

A pump 9l fed from a reservoir 92 is connected to two solenoid operated reversing valves 93 and hence to the two double acting rams 90. The reversing valves are also connected to the reservoir 92. Each valve is controlled by two

solenoids

95, 96 and the solenoids are controlled automatically from microswitches attached to the wheel mountings. the microswitches being settable in a position corresponding to a required depth of cut. Thus the height of the wheel 45 is adjusted automatically after an initial setting and the depth of cut is kept constant even if, for example. fluid were to leak past the pistons of the rams 90 during prolonged use.

Hydraulic accumulators 97 are provided in the circuits leading to the vertically uppermost sides of the rams 90 to cushion any shock loads applied to the wheels 45.

To carry out a machining operation the wheels 45 are adjusted in height automatically by the circuit of FIG. 7. If a different depth of cut from that set by the micro switches is required the electrical circuit to the solenoids can be overriden from the cab. For example. if the cut is to be deeper at one side that at the other then the wheel 45 at that one side is set higher relative to the drum. Ram 43 is then completely released allowing the drum to move into contact with the road surface under its own weight and the apparatus is driven slowly along the surface of a road in a forward direction with the ram 68 (FIG. 6) maintaining the hydrostatic circuit in the planing condition. The burner assembly 18 heats and softens the road surface and drum I9 is driven in the opposite direction to that of the road wheels to cut away a layer of road surface. If the road surface is cambered the wheels 45 automatically angle the drum. tube 40 pivoting about the chassis.

When it is desired to transfer the machine from site to site the ram 68 is used to move the hydrostatic cir can to the transit k'tll'ttllllttll.

The invention is not restricted to the details of the foregoing example. For instance the 7 feet 6 inches wide drum l9 and burner assembly 18 may be replaced hy wider devices. Where the width of the de\iees exceeds the overall width of the apparatus the burner assembly and drum may be mounted on one or more turntable devices so that for mmement of the apparatus from site to site the devices may he rotated in a hor izontal plane to swing the protruding ends of the devices inwardly so that they lie within the overall width of the apparatus.

lhere may two or more chevrons or \"s of teeth spaced circumferentially about the cutting drum.

One important advantage of the machine just described is that the hydrostatic drive to the drum and the road wheels gives an infinitely variable speed range to the drive and the road wheels. This feature is not available with conventional mechanical devices.

I claim:

1. Apparatus for machining road surfaces of the kind comprising a body having road wheels and carrying a cutting drum mounted for rotation about an axis extending transversely of the direction of travel and movable into contact with a road surface to cut away a layer of the surface in which there is a first hydrostatic pump connected to a hydrostatic motor for driving the drum in which there is a second hydrostatic pump connected to a hydrostatic motor for driving at least one of the road wheels and in which there is means to drive both of the pumps at constant speedand both of the pumps have infinitely variable displacements, means being provided for varying the displacements of the pumps individually whereby any combination of drum and road wheel speeds may be provided. and valve means for connecting the pumps to the motors in a road machining position wherein the first pump is connected to the drum motor and the second pump is connected to 6 the road wheel motor and a transit position wherein the first pump is connected to the road wheels 2. Apparatus as claimed in claim I in which the pumps are swash plate pumps driven by a single engine arranged to be driven at constant speed and the speed at which the motors are driven is variable by varying the angle of the swash plates.

3. Apparatus as claimed in claim 1 in which a hydrostatic motor for the drum is mounted at least partly within the drum.

4. Apparatus as claimed in claim 3 in which the drum is arranged to be driven by two hydrostatic motors of which the rotors are arranged for rotation about the same axis the drum being mounted on the two rotors.

5. Apparatus as claimed in claim 1 in which the drum is arranged to be driven in a direction of rotation opposed to that of the road wheels.

6. Apparatus as claimed in claim 5 including means for heating the road surface in advance of the drumv 7. Apparatus as claimed in claim 1 including means to split the flow of fluid to the wheel motor to alter the speed of rotation of the wheel motor.

8. Apparatus as claimed in claim 1 including at least one jockey wheel to control the depth of cut of the drum in which there is at least one double acting hydraulic ram to control the position of the jockey wheel and pump means to operate the ram there being in the hydraulic connection between the pump means and the ram a hydraulic accumulator to absorb shock loads on the jockey wheel.

9. Apparatus as claimed in claim 8 in which there is means to detect the position of the jockey wheel and means to operate the ram in a sense to move the jockey wheel back to a predetermined position if the detection means detects movement of the wheel from the said predetermined position.

10. Apparatus as claimed in claim 9 in which the detection means comprises microswitches settable in a position corresponding to a desired cutting depth.

Claims

1. Apparatus for machining road surfaces of the kind comprising a body having road wheels and carrying a cutting drum mounted for rotation about an axis extending transversely of the direction of travel and movable into contact with a road surface to cut away a layer of the surface in which there is a first hydrostatic pump, connected to a hydrostatic motor For driving the drum in which there is a second hydrostatic pump connected to a hydrostatic motor for driving at least one of the road wheels and in which there is means to drive both of the pumps at constant speed, and both of the pumps have infinitely variable displacements, means being provided for varying the displacements of the pumps individually whereby any combination of drum and road wheel speeds may be provided, and valve means for connecting the pumps to the motors in a road machining position wherein the first pump is connected to the drum motor and the second pump is connected to the road wheel motor and a transit position wherein the first pump is connected to the road wheels.

2. Apparatus as claimed in claim 1 in which the pumps are swash plate pumps driven by a single engine arranged to be driven at constant speed and the speed at which the motors are driven is variable by varying the angle of the swash plates.

4. Apparatus as claimed in claim 3 in which the drum is arranged to be driven by two hydrostatic motors of which the rotors are arranged for rotation about the same axis, the drum being mounted on the two rotors.

6. Apparatus as claimed in claim 5 including means for heating the road surface in advance of the drum.

7. Apparatus as claimed in claim 1 including means to split the flow of fluid to the wheel motor to alter the speed of rotation of the wheel motor.

8. Apparatus as claimed in claim 1 including at least one jockey wheel to control the depth of cut of the drum in which there is at least one double acting hydraulic ram to control the position of the jockey wheel and pump means to operate the ram, there being in the hydraulic connection between the pump means and the ram a hydraulic accumulator to absorb shock loads on the jockey wheel.