Split drum and support arrangement for a compacting work machine

A split drum is provided for a compacting work machine and includes a first and a second drum section. A support arrangement defines a housing that surrounds a vibratory mechanism and is adapted to support the first and second drum sections. The support arrangement comprises a first support member and a second support member that are rotatably connected. Rotational power may be supplied to the first and second drum sections through the use of a propel motor. The first and second drum sections may be rotated at equal speeds or different speeds relative to one another.

TECHNICAL FIELD

The invention relates generally to asphalt and soil compacting work machines, and more particularly to a support arrangement adapted to support a split drum for such work machines.

BACKGROUND

Compacting work machines are commonly employed for compacting freshly laid asphalt, soil, and other compactable substrates. For example these work machines may include plate type compactors or rolling drum compactors with one or more drums. The drum type work machines function to compact the material over which the machine is driven. In order to more efficiently compact the material the drum assembly often includes a vibratory mechanism for inducing vibratory forces on the material being compacted.

It is common practice in the compacting of asphalt to use work machines that include two rotating drums to more efficiently compact the material. Double drum compactors are used so that during each pass over the material being compacted each drum performs a portion of the compacting process. These double drum compactors either have an articulating frame or each drum has the ability to pivot about a vertical axis so that the work machine can be steered in a desired direction during operation. During tight turning operations the portion of the drum that is radially outward of the turn can slide over the material being compacted. This sliding can cause a tear in the material because the portion of the drum that is radially outward of the turn desires to rotate faster than the inner portion. On the other hand the inner portion of the drum can plow or mound the asphalt because the tendency is for the inner portion of the drum to rotate slower than the outside portion. Both of the above-described tendencies are contrary to the goal of finishing a road surface that is smooth and flat.

A solution in an attempt to minimize the problem set forth above is to provide a drum that has first and second drum sections known as a split drum. The split drum divides the width of a given drum in half allowing an outer drum section to rotate faster than an inner drum section during turning operations. Split drum designs are known in the art and often use a fixed friction pack to couple the two drum sections to one another, such as seen in a Hamm Operating and Service Manual (DV-6, Edition 04 83). This reference teaches having an offset support arrangement wherein the friction pack is offset to one side and the vibratory mechanism is offset to the other side. This imbalance in the drum and results in poor compacting on one side and not the other. Additionally, the frictional force of the friction packs must be overcome however before slip can occur between the drum sections. In operation however these split drums do not always operate in a predictable manner and slip between the sections occurs when not desired and often does not occur when slip is desired. Another attempt to address this problem is disclosed in U.S. Pat. No. 5,390,495 granted on Feb. 21, 1995 and assigned to Poclain Hydraulics. This patent teaches having first and second drum sections that are coupled together by a brake arrangement and using independent drive motors to propel each drum section.

The present invention is directed at overcoming one or more of the problems as set forth above.

SUMMARY OF THE INVENTION

In one aspect of the present invention, a support arrangement adapted to support a split drum of a compacting machine is provided. The support arrangement includes a first support member and a second support member rotatably connected to each other. The support arrangement defines a housing that surrounds a vibratory mechanism of the split drum.

In yet another aspect of the present invention, a split drum rotatably supporting a main frame of a compacting work machine is provided. The split drum includes a first drum section, a second drum section, a housing and a vibratory mechanism. The housing is defined by a support arrangement and surrounds a vibratory mechanism of the split drum. The support arrangement rotatably supports the first drum section and the second drum section.

DETAILED DESCRIPTION

A work machine10, for increasing the density of a compactable material or mat12such as soil, gravel, or bituminous mixtures is shown inFIG. 1. The work machine10is for example, a double drum vibratory compactor, having a first/front compacting drum14and a second/rear compacting drum16rotatably mounted on a main frame18. The main frame18also supports an engine20that has at least one power source22,24conventionally connected thereto. Variable displacement fluid pumps or electrical generators can be used as interchangeable alternatives for power sources22,24without departing from the present invention.

In as much as, the front drum14and the rear drum16are structurally and operatively similar. The description, construction and elements comprising the front drum14will now be discussed in detail and applies equally to the rear drum16. Referring toFIG. 2, the front drum14includes a vibratory mechanism26that is operatively connected to a vibratory motor28. The vibratory motor28is operatively connected, as by fluid conduits and control valves or electrical conductors and switches neither of which are shown, to the power source22,24.

The front drum14is a split drum15that includes a first and a second drum section30,32. Each of the first and second drum sections30,32is made up of an outer shell34that is manufactured from a steel plate that is rolled and welded at the joining seam. A first bulkhead36is fixedly secured to the inside diameter of the outer shell34of the first drum section30as by welding and a second bulkhead38is fixedly secured to the inside diameter of the outer shell34of the second drum section32in the same manner.

The first and second drum sections30,32are vibrationally isolated from the main frame18by rubber mounts40. A first propel motor42is positioned between the main frame18and the first drum section30. For example, the first propel motor42is connected to a first mounting plate46and an output of the first propel motor43is connected to the first bulkhead36and a first support member52, by fasteners. The rubber mounts40are positioned between and connected to the main frame18and the first mounting plate46. The first propel motor42additionally is operatively connected to the power source22,24which, supplies a pressurized operation fluid or electrical current, to first propel motor42for propelling the first drum section30.

In a similar manner, a second propel motor44is positioned between the main frame18and the second drum section32. Rubber mounts40are positioned between and connected to the main frame18and the second mounting plate48. The second propel motor44is connected to the second mounting plate48and an output of the second propel motor45is connected to the second bulkhead38and a second support member54, by fasteners, the second support member, in this embodiment, being made of two pieces. The second propel motor44additionally is operatively connected to the power source22,24which, supplies a pressurized operation fluid or electrical current, to second propel motor44for propelling the second drum section32.

The vibratory mechanism26includes a first/inner eccentric weight60and a second/outer eccentric weight62that are connected to a vibratory mechanism shaft64. The first/inner eccentric weight60, being a movable weight, and the second/outer eccentric weight62, being a stationary weight, are rotatably supported within a housing58by bearings68. The vibratory motor28, when driven in a first direction, supplies a rotational power to the vibratory mechanism26thereby imparting a vibratory force, having a first amplitude, on compacting drum14. When the vibratory28is driven in an opposite direction to supply rotational power to the vibratory mechanism26, a vibratory force having a second amplitude is imparted on the compacting drum14. The amplitude of the vibratory mechanism26may be set manually, having two or more amplitude settings, or automatically, having an infinitely variable amplitude, depending on the type of vibratory mechanism26being used.

About the vibratory mechanism is a support arrangement50which is part of a housing58that rotatably connects the first drum section30to the second drum section32. The support arrangement50is rotatably connected between the first and second bulkheads36,38to enable the first and second drum section30,32to rotate in relation to one another. As mentioned above, the first support member52is connected to the first bulkhead36and the output of the first propel motor43by fasteners. The second support member54, being made up of two separate pieces connected by fasteners, is connected to the second bulkhead38and the output of the second propel motor45by fasteners. Although the second support member54as shown in this embodiment is made of two separate pieces, it may also be one complete piece. The first support member52is rotatably positioned inside the second support member54and rotatably connected by a bearing arrangement. In this case, the bearing arrangement consists of tapered roller bearings56. The support arrangement50allows the first propel motor42to rotate the first drum section30about the vibration mechanism26at either the same rate or at a different rate than the second propel motor44rotates the second drum section32about the vibration mechanism26.

Of course, this is but one of a number of arrangements that the support arrangement50may assume. For example, the second support member54may be rotatably positioned outside the first support member52. The first support member52may also be rotatably positioned outside the second support member54. Another example may have the first and second support members52,54come together at the bearing arrangement where they may be rotatably connected without any overlap of the first and second support members52,54. Additionally, the bearing arrangement that may be seen in any of the embodiments may comprise, but is not limited to, tapered roller bearings, ball bearings, and bronze bushings.

In an alternative embodiment of the present disclosure (not shown), the first and second drum sections30,32may be rotatably connected by a support arrangement50and a one of the first and second drum sections30,32may be rotatably driven by a single propel motor. The other of the first and second drum sections30,32may be rotatably controllable by a brake mechanism (not shown). The brake mechanism may comprise, but is not limited to, a caliper and disc brake arrangement capable of locking the first drum section30to the second drum section32. The brake mechanism may also allow the first drum section30to rotate at a different rate than the second drum section32. In one embodiment, the caliper (not shown) could be attached to the inside diameter of the first drum section30and the associated disc (not shown) could be attached to the housing58and extend sufficiently outward toward the inner diameter of the second drum section32such that the caliper is operable to engage the disc.

INDUSTRIAL APPLICABILITY

In operation rotational/propel power is supplied to the first/front drum14by the first and second propel motors42,44. Power from the first and second propel motors42,44is transmitted through the first and second support members52,54of the support arrangement50. The support arrangement50is used to support the relative movement between the first and second drum sections30,32. The support arrangement50creates a rigid joint between the first and second drum sections30,32such that the first and second drum sections30,32are free to rotate at equal or different speeds as may be demanded during operation of the compactor so the drums do not tear the compacting material12during tight turning operations.

In alternate embodiments of the present disclosure, such as when a single propel motor is used in conjunction with a brake mechanism (not shown), the first or second drum section30,32will be locked to the other of the first or second drums section30,32as the brake mechanism is engaged such that the single propel motor will cause the first and second drum sections30,32to rotate at an equal rate. When the brake mechanism is disengaged, one of the first and second drum sections30,32will be allowed to rotate faster or slower than the other of the first and second drum section30,32during tight turning operations.

The split drum15provided offers an effective means of overcoming the undesirable characteristics of known unitary drum configurations. In addition to providing an improved support arrangement50, the vibratory mechanism efficiency may also be improved through reduction in weight by only requiring one vibratory mechanism. Centering of the vibratory mechanism with this support arrangement50will help balance the first and second drum sections30,32such that compaction of the compactable material12is equal. Furthermore, loading and sealing of the support arrangement50has been improved over prior support arrangements with the separation of the bearing arrangement with the first and second support members52,54. The support arrangement50may be further improved by widening the first and second support members52,54and spreading out the bearing arrangement even farther about the vibratory mechanism26.