Patent Description:
Work vehicles such as dump trucks and hydraulic excavators are known as construction machines.

For example, Patent Document <NUM> below describes a dump truck that includes a vehicle body frame, a mount device mounted on the vehicle body frame, and a cab connected to the mount device to be rotatable (tilt-up, tilt-down) via a connecting pin. The vehicle body frame is provided with a stopper having an insertion hole through which the connecting pin is inserted. A gap is formed between the insertion hole of the stopper and the connecting pin to restrict the amount of displacement of the connecting pin in a radial direction beyond a predetermined amount. The connecting pin is provided movably in an axial direction of the connecting pin. A gap-filling member is integrally provided on the outer periphery of the connecting pin to be inserted into and pulled out of the gap as the connecting pin moves.

For example, Patent Document <NUM> below describes a hydraulic excavator that includes a swinging frame provided with a swing-type work device on the front side thereof, a floor plate having a driver's seat provided on the swinging frame to be tiltable with the front side thereof as a fulcrum, and a plurality of floor plate support mechanisms provided between a front side position of the swinging frame and a front side position of the floor plate for tiltably supporting the floor plate. The plurality of floor plate support mechanisms are constituted by a central floor plate support mechanism and left and right floor plate support mechanisms provided on the left and right sides of the central floor plate support mechanism. The central floor plate support mechanism is provided with a displacement restricting portion that allows the front position of the floor plate to move vertically with respect to the swinging frame when the floor plate is at a horizontal position and restricts the vertical displacement of the floor plate when the floor plate is at a tilt position. The left and right floor plate support mechanisms are provided with frame side bearings. Each frame side bearing is provided with an elastic member that elastically deforms between the frame side bearing and a connecting pin attached to a floor plate side bearing. The displacement restricting portion is constituted by upper and lower vertical cutout grooves provided in the frame side bearing to cut a pin hole in the vertical direction with a width smaller than the diameter of the pin hole and narrow shaft portions which are cut out at positions of the connecting pin facing the cutout grooves in parallel to the cutout grooves with a width dimension smaller than the width dimension of the cutout grooves. The central floor plate support mechanism is provided with a tilting stopper that restricts the tilting motion of the floor plate at a predetermined angular position when the floorboard is tilted. A further relevant prior art is known from <CIT>.

In the case of Patent Document <NUM>, when the cab rotates in the tilt-up direction or the tilt-down direction, it is necessary to move the connecting pin together with the gap filling member and push the gap filling member into the insertion hole. On the other hand, when the connecting pin returns to its original position, it is necessary to pull the gap filling member out of the gap. Since it is necessary to push and pull out the gap-filling member, there is room for improvement in enhancing workability.

In the case of Patent Document <NUM>, when the floor plate is disposed in a horizontal position, the narrow shaft portion of the connecting pin can be vertically displaced within each cutout groove of the frame side bearing. When the narrow shaft portion of the connecting pin enters the cutout groove, the rotation of the connecting pin is restricted. In a case where the connecting pin rotates from a state in which the narrow shaft portion of the connecting pin has entered the cutout groove, it is necessary to align the center of rotation of the connecting pin with the center of the pin hole, and thus there is room for improvement in enhancing workability.

Accordingly, an object of the present invention is to provide a cab support structure and a construction machine capable of enhancing workability.

According to an aspect of the present invention, there is provided a cab support structure including: a mount device provided on a vehicle body frame; and a connecting mechanism that connects a cab provided above the vehicle body frame via the mount device to the vehicle body frame to be rotatable between a seated position and a tilt position, wherein the connecting mechanism includes a connecting shaft that is connected to the mount device and extends in a horizontal direction, a displacement allowing member connected to the vehicle body frame, and an interlocking member that is connected to the cab and is rotatable in interlock with rotation of the cab, wherein the displacement allowing member has a displacement allowing hole that allows displacement of the connecting shaft in a vertical direction and allows rotation of the connecting shaft between the seated position and the tilt position, and wherein the interlocking member has a displacement allowing portion that allows displacement of the connecting shaft in the vertical direction at the seated position, and a displacement restricting portion that restricts downward displacement of the connecting shaft at the tilt position.

According to the above aspect, it is possible to enhance workability.

In the embodiment, a dump truck will be described as an example of a construction machine (a working vehicle).

As shown in <FIG>, a dump truck <NUM> is a construction machine and includes a vehicle front portion <NUM> and a vehicle rear portion <NUM>. Hereinafter, a forward direction, a backward direction, and a vehicle width direction of the dump truck <NUM> are referred to as a "vehicle forward direction (one side in a vehicle front-rear direction)," a "vehicle rearward direction (the other side in the vehicle front-rear direction)," and a "vehicle width direction. " The vehicle width direction may also be referred to as a "left side (one side in the vehicle width direction)" or a "right side (the other side in the vehicle width direction). " A right-hand side with respect to a direction in which the dump truck <NUM> moves forward is referred to as the right side, and a left-hand side with respect to a direction in which the dump truck <NUM> moves forward is referred to as the left side. A vertical direction, an upward direction, and a downward direction in a state where the dump truck <NUM> is disposed on a horizontal plane are simply referred to as a "vertical direction," an "upward direction," and a "downward direction.

The vehicle front portion <NUM> includes a front frame <NUM> (a vehicle body frame), front wheels <NUM>, a hood <NUM>, and a cab <NUM>.

The front frame <NUM> constitutes a frame of the vehicle front portion <NUM>. The hood <NUM> is attached to the front portion of the front frame <NUM> to be openable and closable. The cab <NUM> is provided above the front frame <NUM>. The cab <NUM> is a roll over protective system (ROPS) cab with a safe structure to ensure the safety of an operator when the dump truck <NUM> overturns.

The vehicle rear portion <NUM> includes a rear frame <NUM>, center wheels <NUM>, and rear wheels <NUM>. The rear frame <NUM> constitutes a frame of the vehicle rear portion <NUM>. The vehicle rear portion <NUM> is provided behind the vehicle front portion <NUM>. The rear frame <NUM> is connected to the front frame <NUM> to be bendable and swingable. A pair of left and right steering cylinders <NUM> bridge between the front frame <NUM> and the rear frame <NUM>. By each steering cylinder <NUM> extending and contracting, the rear frame <NUM> can be bent with respect to the front frame <NUM>, thereby enabling a steering operation.

The vehicle rear portion <NUM> includes a dump body <NUM> and lift cylinders <NUM>. The dump body <NUM> is provided above the rear frame <NUM>. The dump body <NUM> is loaded with a load such as earth. The lift cylinders <NUM> are provided between the left and right sides of the front portion of the dump body <NUM> and the rear frame <NUM>. A lower rear portion of the dump body <NUM> is rotatably attached to the rear frame <NUM>. The dump body <NUM> rotates as the lift cylinders <NUM> expand and contract.

A pair of front wheels <NUM> are provided on the front frame <NUM> to be spaced apart in a vehicle width direction. A pair of center wheels <NUM> are provided on the front portion of the rear frame <NUM> to be spaced apart in the vehicle width direction. A pair of rear wheels <NUM> are provided on the rear portion of the rear frame <NUM> to be spaced apart in the vehicle width direction. When the front wheels <NUM>, the center wheels <NUM>, and the rear wheels <NUM> are driven, the dump truck <NUM> moves forward or backward.

As shown in <FIG>, the cab <NUM> is rotatable in a direction of arrow TU (a tilt-up direction) and a direction of arrow TD (a tilt-down direction) in a state where it is fixedly supported by the front frame <NUM> via a pair of rear side support structures 29B. Various devices <NUM> such as an engine, a torque converter, a transmission, and a hydraulic pump are provided in a space below the hood <NUM> and the cab <NUM>.

Front side support structures 29A and rear side support structures 29B are provided as cab support structures between the cab <NUM> and the front frame <NUM>. A pair of front side support structures 29A are provided between the front portion of the cab <NUM> and the front frame <NUM> to be spaced apart in the vehicle width direction. The pair of rear side support structures 29B are provided between the rear portion of the cab <NUM> and the front frame <NUM> to be spaced apart in the vehicle width direction. Hereinafter, an initial position before the cab <NUM> rotates in the direction of arrow TU will be referred to as a "seated position" (see <FIG>, <FIG>, <FIG>, and <FIG>). Hereinafter, a position where the cab <NUM> is rotated by a predetermined rotation angle in the direction of arrow TU from the seated position is referred to as a "tilt position" (see <FIG>, <FIG>, and <FIG>). At the seated position of the cab <NUM>, both the left and right sides of the front portion and both the left and right sides of the rear portion of the cab <NUM> are supported by the cab support devices 29A and 29B.

For example, when inspecting or maintaining the various devices <NUM>, the operator opens the hood <NUM> and further disassembles the front side support structure 29A. For example, by extracting a connecting shaft (not shown) from each front side support structure 29A, it is possible to release a support state of the cab <NUM> on both the left and right sides of the front portion of the cab <NUM> by mount devices. After releasing the support state, the operator rotates the cab <NUM> in the direction of arrow TU using operating power of a hydraulic cylinder, a crane, or the like. As a result, the upper sides of the various devices <NUM> are exposed. When a support rod <NUM> is inserted between the cab <NUM> and the front frame <NUM> in a state where the cab <NUM> is rotated, the cab <NUM> is held at a predetermined rotation angle.

The rear side support structure 29B will be described below as the cab support structure. As the rear side support structure 29B, one of the pair of left and right rear side support structures 29B will be described. Since the other rear side support structure 29B has the same configuration as the one rear side support structure 29B, detailed description thereof will be omitted.

As shown in <FIG>, the rear side support structure 29B includes a mount device <NUM>, a connecting mechanism <NUM>, and a cover <NUM>.

The mount device <NUM> is a device that supports the cab <NUM>. The mount device <NUM> is provided on the front frame <NUM>. The mount device <NUM> is fixed to the front frame <NUM> by a fastening member such as a bolt. The mount device <NUM> is filled with a viscous fluid (liquid) such as silicone oil. The mount device <NUM> is a liquid-filled type mount device <NUM>. As shown in <FIG>, the mount device <NUM> includes a movable shaft <NUM>, a cup <NUM>, and a cushion rubber <NUM>.

The movable shaft <NUM> is formed in a circular column shape. The movable shaft <NUM> extends in the vertical direction. The cup <NUM> is closed in a liquid-tight state by the movable shaft <NUM> and the cushion rubber <NUM>. The cushion rubber <NUM> is provided integrally with the outer periphery of the movable shaft <NUM>. For example, in a case where vibration occurs in the cab <NUM>, the vibration is transmitted to the mount device <NUM> via the connecting mechanism <NUM>. The vibration transmitted to the mount device <NUM> displaces the movable shaft <NUM>. The silicone oil is agitated due to the displacement of the movable shaft <NUM>. The vibration of the cab <NUM> is damped by viscous resistance when the silicone oil is agitated.

The connecting mechanism <NUM> connects the cab <NUM> to the front frame <NUM> via the mount device <NUM> to be rotatable between the seated position and the tilt position. The connecting mechanism <NUM> includes a mount side bracket <NUM>, a cab side bracket <NUM> (a connecting member), displacement allowing members 60A and 60B, a connecting shaft <NUM>, and an interlocking member <NUM>.

The mount side bracket <NUM> is formed in a U shape with a bottom portion <NUM> and side portions <NUM>.

The bottom portion <NUM> is fixed to the movable shaft <NUM> of the mount device <NUM> with a bolt <NUM>. The side portions <NUM> are formed integrally with both the left and right ends of the bottom portion <NUM> to protrude upward therefrom. As shown in <FIG>, mount side attachment holes <NUM> to which the connecting shaft <NUM> is attached are provided in portions of the pair of side portions <NUM> that face each other. A boss portion <NUM> protruding inward is provided on the outer periphery of each of the mount side attachment holes <NUM>.

The cab side bracket <NUM> includes a plate portion <NUM>, a base portion <NUM>, and an attachment portion <NUM>.

The plate portion <NUM> is formed in a plate shape along the attachment surface of the cab <NUM>. The plate portion <NUM> is fixed to the attachment surface of the cab <NUM> by, for example, welding or the like. The base portion <NUM> protrudes rearward from the plate portion <NUM>. The base portion <NUM> is fixed to the plate portion <NUM> by, for example, welding or the like. The attachment portion <NUM> is formed in a cylindrical shape that opens in the vehicle width direction. The attachment portion <NUM> is fixed to the rear end of the base portion <NUM> by, for example, welding or the like.

As shown in <FIG>, the attachment portion <NUM> has a cab side attachment hole <NUM> (an insertion hole) through which the connecting shaft <NUM> is inserted. The connecting shaft <NUM> is attached to the cab side attachment hole <NUM> via a metal bushings <NUM> inserted from both the left and right sides of the cab side attachment hole <NUM>. An annular shim <NUM> is provided between the bushing <NUM> and the boss portion <NUM>. As shown in <FIG>, the attachment portion <NUM> is provided with a grease supplying nipple <NUM> for supplying lubricating oil such as grease to the interior of the attachment portion <NUM>.

As shown in <FIG>, the mount side attachment hole <NUM> and the cab side attachment hole <NUM> are provided such that their centers are coaxial with each other. The inner diameter dimension of the mount side attachment hole <NUM> and the inner diameter dimension of the bushing <NUM> are substantially equal to the outer diameter dimension of the connecting shaft <NUM>. The outer diameter dimension of the bushing <NUM> is substantially equal to the inner diameter dimension of the cab side attachment hole <NUM>. The cab <NUM> is supported by the mount device <NUM> with almost no gap via the cab side bracket <NUM>, the connecting shaft <NUM>, and the mount side bracket <NUM>.

A pair of displacement allowing members 60A and 60B are provided. The pair of displacement allowing members 60A and 60B are disposed with spacing in the vehicle width direction. The mount device <NUM> is disposed between the pair of displacement allowing members 60A and 60B in the vehicle width direction. The pair of displacement allowing members 60A and 60B are a first displacement allowing member 60A provided on a first end side of the connecting shaft <NUM> in an axial direction and a second displacement allowing member 60B provided on a second end side of the connecting shaft <NUM> in the axial direction, the connecting shaft <NUM> extending in the vehicle width direction (a horizontal direction).

The first displacement allowing member 60A includes a plate-shaped first vertical plate portion 61A extending in the vertical direction and a plate-shaped first horizontal plate portion 62A extending in a front-rear direction (the horizontal direction). In a cross-sectional view of <FIG>, the first displacement allowing member 60A has an L-shaped cross-sectional shape.

The first vertical plate portion 61A has a first end side hole 63A (a displacement allowing hole) that opens in the axial direction of the connecting shaft <NUM>. The first end side hole 63A allows the displacement of the connecting shaft <NUM> in the vertical direction. The first end side hole 63A allows the rotation of the connecting shaft <NUM> between the seated position and the tilt position. At the position shown in <FIG>, the center of the first end side hole 63A is coaxial with the mount side attachment hole <NUM> and the cab side attachment hole <NUM>. The inner diameter dimension of the first end side hole 63A is larger than the outer diameter dimension of the connecting shaft <NUM> by a predetermined value (<NUM> × St).

The first horizontal plate portion 62A is fixed to the lower end of the first vertical plate portion 61A by, for example, welding or the like. The lower end of the first vertical plate portion 61A is fixed to the inner portion (a portion near the mount side bracket <NUM>) of the first horizontal plate portion 62A in the vehicle width direction. The first horizontal plate portion 62A is fixed to the front frame <NUM> by a fastening member such as a bolt <NUM>. The first horizontal plate portion 62A has an upper surface 65A which is parallel to the horizontal direction.

The second displacement allowing member 60B includes a plate-shaped second vertical plate portion 61B (a vertical plate portion) of a plate shape extending in the vertical direction and a plate-shaped second horizontal plate portion 62B (a horizontal plate portion) extending in a front-rear direction (the horizontal direction). In a cross-sectional view of <FIG>, the second displacement allowing member 60B has an inverted L-shaped cross-sectional shape.

The second vertical plate portion 61B has a second end side hole 63B (a displacement allowing hole) that opens in the axial direction of the connecting shaft <NUM>. The second end side hole 63B allows the displacement of the connecting shaft <NUM> in the vertical direction. The second end side hole 63B allows the rotation of the connecting shaft <NUM> between the seated position and the tilt position. At the position shown in <FIG>, the center of the second end side hole 63B is coaxial with the mount side attachment hole <NUM> and the cab side attachment hole <NUM>. The inner diameter dimension of the second end side hole 63B is larger than the outer diameter dimension of the connecting shaft <NUM> by a predetermined value (<NUM> × St). For example, the first vertical plate portion 61A and the second vertical plate portion 61B may be formed in the same shape.

The second horizontal plate portion 62B is fixed to the lower end of the second vertical plate portion 61B by, for example, welding or the like.

The lower end of the second vertical plate portion 61B is fixed to the central portion of the second horizontal plate portion 62B in the vehicle width direction. The second horizontal plate portion 62B is fixed to the front frame <NUM> by a fastening member such as a bolt <NUM>. The second horizontal plate portion 62B has an upper surface 65B which is parallel to the horizontal direction. For example, the first horizontal plate portion 62A and the second horizontal plate portion 62B may be formed the same shape.

Each of the displacement allowing members 60A and 60B is detachably connected to the front frame <NUM> via a fastening member such as a bolt <NUM>. Each of the displacement allowing members 60A and 60B is formed of a material of a hardened metal. Each of the displacement allowing members 60A and 60B is formed of a material of a hardened steel plate, for example.

The connecting shaft <NUM> is formed in a circular column shape extending in the vehicle width direction. The connecting shaft <NUM> is connected to the interlocking member <NUM> which will be described later. Both ends of the connecting shaft <NUM> protrude outward in the vehicle width direction with respect to the first vertical plate portion 61A and the second vertical plate portion 61B. A space S having a dimension in a radial direction of St is formed between the outer peripheral surface of the connecting shaft <NUM> and the inner peripheral surface of each of the end holes 63A and 63B. Due to the existence of this space S, the connecting shaft <NUM> can be displaced in the radial direction (the vertical direction in <FIG>) by the dimension St. In other words, the connecting shaft <NUM> is restricted from being displaced by a predetermined amount of displacement of St or more by the displacement allowing members 60A and 60B.

The interlocking member <NUM> is connected to the connecting shaft <NUM>. The interlocking member <NUM> is disposed between the mount side bracket <NUM> and the second displacement allowing member 60B. The interlocking member <NUM> is disposed with spacing from the second vertical plate portion 61B of the second displacement allowing member 60B in the vehicle width direction. The interlocking member <NUM> is formed in a plate shape extending parallel to the second vertical plate portion 61B.

The interlocking member <NUM> has a connecting hole <NUM> through which the connecting shaft <NUM> is inserted. A boss portion <NUM> protruding inward is provided on the outer periphery of the connecting hole <NUM>. The center of the connecting hole <NUM> is coaxial with the mount side attachment hole <NUM> and the cab side attachment hole <NUM>. The inner diameter dimension of the connecting hole <NUM> is substantially equal to the outer diameter dimension of the connecting shaft <NUM>.

The interlocking member <NUM> is connected to the cab side bracket <NUM> via the connecting shaft <NUM>, a cylindrical member <NUM>, and a bolt <NUM>. The interlocking member <NUM> is connected to the cab <NUM> via the cab side bracket <NUM>. The interlocking member <NUM> is rotatable in interlock with the rotation of the cab <NUM>. The interlocking member <NUM> is provided with a bolt insertion hole <NUM> that opens in the vehicle width direction. The cylindrical member <NUM> is formed in a cylindrical shape extending in the vehicle width direction from the surface of base portion <NUM> of cab side bracket <NUM> facing the upper portion of the interlocking member <NUM> toward the interlocking member <NUM>. An end portion of the cylindrical member <NUM> on a side of the base portion <NUM> is fixed to the base portion <NUM> by welding or the like. A portion of the cylindrical member <NUM> on a side of the interlocking member <NUM> is fixed to the upper portion of the interlocking member <NUM> by the bolt <NUM> through the bolt insertion hole <NUM>.

The interlocking member <NUM> is detachably connected to the cab <NUM> via the bolt <NUM> or the like. The interlocking member <NUM> is formed of a material of a hardened metal. The interlocking member <NUM> is formed of a material of a hardened steel plate, for example. For example, the interlocking member <NUM> may be formed of the same member as the displacement allowing members 60A and 60B.

As shown in <FIG>, the interlocking member <NUM> includes a displacement allowing portion <NUM> that allows the displacement of the connecting shaft <NUM> and a displacement restricting portion <NUM> that restricts the displacement of the connecting shaft <NUM>. The displacement allowing portion <NUM> and the displacement restricting portion <NUM> are continuous along the outer periphery of the interlocking member <NUM>.

<FIG> is a view showing a state when the cab <NUM> is at the seated position in the axial direction of the connecting shaft <NUM>.

The displacement allowing portion <NUM> allows the displacement of the connecting shaft <NUM> in the vertical direction at the seated position. At the seated position, a gap G is provided between the displacement allowing portion <NUM> and the upper surface 65B of the second horizontal plate portion 62B to allow the displacement of the connecting shaft <NUM> in the vertical direction. As shown in <FIG>, at the seated position, the vertical dimension Gt of the gap G is larger than the vertical dimension St of the space S (the spacing between the inner surface of the displacement allowing hole and the connecting shaft <NUM>). As shown in <FIG>, the displacement allowing portion <NUM> has a first flat surface P1 parallel to the horizontal direction at the seated position. At the seated position, the first flat surface P1 is parallel to the upper surface 65B of the second horizontal plate portion 62B.

<FIG> is a view showing a state when the cab <NUM> is at the tilt position in the axial direction of the connecting shaft <NUM>.

The displacement restricting portion <NUM> restricts the downward displacement of the connecting shaft <NUM> at the tilt position. At the tilt position, the displacement restricting portion <NUM> is in contact with the upper surface 65B of the second horizontal plate portion 62B. The displacement restricting portion <NUM> has a second flat surface P2 (a flat surface) along the upper surface 65B of the second horizontal plate portion 62B at the tilt position.

<FIG> is a view showing a state when the interlocking member <NUM> in <FIG> is rotated from the tilt position to a lift-up position.

The cab <NUM> is rotatable to the lift-up position inclined more than the tilt position. The displacement restricting portion <NUM> includes a first restricting portion <NUM> that is in contact with the upper surface 65B of the second horizontal plate portion 62B at the tilt position and a second restricting portion <NUM> that is in contact with the upper surface 65B of the second horizontal plate portion 62B at the lift-up position.

As shown in <FIG>, the first restricting portion <NUM> has the second flat surface P2 (a flat surface) along the upper surface 65B of the second horizontal plate portion 62B at the tilt position.

As shown in <FIG>, the second restricting portion <NUM> has an arc-shaped curved surface P3 that curves outward in the radial direction of the connecting shaft <NUM> when viewed in the axial direction along the connecting shaft <NUM>. The first flat surface P1, the second flat surface P2, and the curved surface P3 are disposed in order in the rotation direction of the interlocking member <NUM>.

As shown in <FIG>, the cover <NUM> is provided on the connecting mechanism <NUM>. The cover <NUM> is formed of an elastic material such as rubber. The cover <NUM> covers the gap G. The cover <NUM> is detachably attached to the plate portion <NUM> of the cab side bracket <NUM> with an attachment pin <NUM> or the like.

The cover <NUM> extends downward from the plate portion <NUM> and covers the connecting mechanism <NUM> from above. The lower end of the cover <NUM> is in contact with the upper surfaces 65A and 65B of the horizontal plate portions 62A and 62B. The cover <NUM> extends across the first vertical plate portion 61A of the first displacement allowing member 60A and the second vertical plate portion 61B of the second displacement allowing member 60B in the vehicle width direction.

Next, the operation when the cab <NUM> is rotated in a tilt-up direction from a tilt-down state (the state at the seated position) will be described.

At the seated position, the cab <NUM> is supported by four cab support structures located on both the left and right sides of the front portion of the cab <NUM> and on both the left and right sides of the rear portion of the cab <NUM>. As shown in <FIG>, at the seated position, the gap G is provided between the displacement allowing portion <NUM> of the interlocking member <NUM> and the upper surface 65B of the second horizontal plate portion 62B of the second displacement allowing member 60B to allow the displacement of the connecting shaft <NUM> in the vertical direction. As shown in <FIG>, at the seated position, the vertical dimension Gt of the gap G is larger than the vertical dimension St of the spacing S between the inner surface of the displacement allowing hole and the connecting shaft <NUM>. At the seated position, the weight of the cab <NUM> is transferred to the mount devices in the four cab support structures on both left and right sides of the front portion of the cab <NUM> and on both left and right sides of the rear portion of the cab <NUM> (the left and right front side support structures 29A and the left and right rear side support structures 29B).

For example, as shown in <FIG>, when the cab <NUM> is rotated in the tilt-up direction from the seated position, if a connecting shaft (not shown) is extracted from each front side support structure 29A, the support state by the mount devices in both the left and right sides of the front portion of the cab <NUM> is released. After releasing the support state, the operator rotates the cab <NUM> in the direction of arrow TU using operating power of a hydraulic cylinder, a crane, or the like.

When the cab <NUM> rotates in the arrow TU direction, the interlocking member <NUM> rotates in interlock with the rotation of the cab <NUM>. As the interlocking member <NUM> rotates, the displacement restricting portion <NUM> of the interlocking member <NUM> approaches the upper surface 65B of the second horizontal plate portion 62B. As shown in <FIG>, at the tilt position, the displacement restricting portion <NUM> (the first restricting portion <NUM>) of the interlocking member <NUM> is in contact with the upper surface 65B of the second horizontal plate portion 62B. At the tilt position, the first restricting portion <NUM> of the interlocking member <NUM> is in contact with the upper surface 65B of the second horizontal plate portion 62B between the flat surfaces.

Hereinafter, the angle formed by the upper surface 65B (the horizontal plane) of the second horizontal plate portion 62B and the straight line along the displacement allowing portion <NUM> of the interlocking member <NUM> when viewed in the axial direction of the connecting shaft <NUM> is referred to as a rotation angle. For example, at the tilt position, when the support rod <NUM> (see <FIG>) is inserted between the cab <NUM> and the front frame <NUM>, the cab <NUM> is held at a predetermined rotation angle A1. For example, at the tilt position, the rotation angle A1 is about <NUM> degrees.

As shown in <FIG>, in order to insert the support rod <NUM> (see <FIG>) between the cab <NUM> and the front frame <NUM>, the cab <NUM> is once rotated to the lift-up position inclined more than the tilt position. At the lift-up position, the second restricting portion <NUM> of the interlocking member <NUM> is in contact with the upper surface 65B of the second horizontal plate portion 62B. In the example of <FIG>, a portion of the second restricting portion <NUM> of the interlocking member <NUM> near the first restricting portion <NUM> is in contact with the upper surface 65B of the second horizontal plate portion 62B. For example, at the lift-up position, a rotation angle A2 is about <NUM> degrees.

After the support rod <NUM> (see <FIG>) is inserted between the cab <NUM> and the front frame <NUM> at the lift-up position, the cab <NUM> is rotated (returned) from the lift-up position to the tilt position. At the tilt position, the weight of the cab <NUM> is transferred to the front frame <NUM> through the interlocking members <NUM> and the second horizontal plate portions 62B of the two cab support structures (the left and right rear side support structures 29B) located on both the left and right sides of the rear portion of the cab <NUM>.

The displacement allowing holes 63A and 63B (see <FIG>) allow the connecting shaft <NUM> to rotate not only between the seated position and the tilt position, but also between the tilt position and the lift-up position. That is, the displacement allowing holes 63A and 63B always allow the connecting shaft <NUM> to rotate between the seated position and the lift-up position.

As described above, the rear side support structure 29B of the present embodiment includes the mount device <NUM> provided on the front frame <NUM> and the connecting mechanism <NUM> that connects the cab <NUM> provided above the front frame <NUM> via the mount device <NUM> to the front frame <NUM> to be rotatable between the seated position and the tilt position, the connecting mechanism <NUM> includes the connecting shaft <NUM> that is connected to the mount device <NUM> and extends in the horizontal direction, the displacement allowing members 60A and 60B connected to the front frame <NUM>, and the interlocking member <NUM> that is connected to the cab <NUM> and is rotatable in interlock with rotation of the cab <NUM>, the displacement allowing members 60A and 60B have the displacement allowing holes 63A and 63B that allow displacement of the connecting shaft <NUM> in the vertical direction and allow rotation of the connecting shaft <NUM> between the seated position and the tilt position, and the interlocking member <NUM> has the displacement allowing portion <NUM> that allows displacement of the connecting shaft <NUM> in the vertical direction at the seated position and the displacement restricting portion <NUM> that restricts downward displacement of the connecting shaft <NUM> at the tilt position.

In the present embodiment, the displacement of the connecting shaft <NUM> in the vertical direction is allowed by the displacement allowing portion <NUM> of the interlocking member <NUM> at the seated position. On the other hand, the downward displacement of the connecting shaft <NUM> is restricted by the displacement restricting portion <NUM> of the interlocking member <NUM> at the tilt position. Therefore, it is not necessary to push or pull the gap filling member into or out of the displacement allowing holes 63A and 63B of the displacement allowing members 60A and 60B. Furthermore, in the present embodiment, the displacement allowing holes 63A and 63B allow the connecting shaft <NUM> to rotate between the seated position and the tilt position, and thus it is not necessary to align the rotation center of the connecting shaft <NUM> and the center of the displacement allowing holes 63A and 63B. Therefore, workability can be improved.

In the present embodiment, the displacement allowing member <NUM> includes the plate-shaped vertical plate portion 61B that has the displacement allowing hole 63B and extends in the vertical direction, and the plate-shaped horizontal plate portion 62B that is coupled to a lower portion of the vertical plate portion 61B, is connected to the front frame <NUM>, and extends in the horizontal direction, the interlocking member <NUM> is formed in a plate shape extending parallel to the vertical plate portion 61B, the displacement allowing portion <NUM> and the displacement restricting portion <NUM> are continuous along an outer periphery of the interlocking member <NUM>, at the seated position, the gap G is provided between the displacement allowing portion <NUM> and the upper surface 65B of the horizontal plate portion 62B to allow the displacement of the connecting shaft <NUM> in the vertical direction, and at the tilt position, the displacement restricting portion <NUM> is in contact with the upper surface 65B of the horizontal plate portion 62B.

As shown in <FIG>, in the present embodiment, the displacement allowing portion <NUM> and the displacement restricting portion <NUM> are continuous along the outer periphery of the interlocking member <NUM>. As shown in <FIG>, at the seated position, the displacement of the connecting shaft <NUM> in the vertical direction is allowed by the gap G between the displacement allowing portion <NUM> of the interlocking member <NUM> and the upper surface 65B of the horizontal plate portion 62B. As shown in <FIG>, at the tilt position, the displacement restricting portion <NUM> of the interlocking member <NUM> is in contact with the upper surface 65B of the horizontal plate portion 62B, and thus the downward displacement of the connecting shaft <NUM> is restricted. Therefore, it is possible to smoothly switch between the displacement allowing state and the displacement restricting state of the connecting shaft <NUM> by rotating the interlocking member <NUM>.

In the present embodiment, at the seated position, the vertical dimension Gt of the gap G is larger than the vertical dimension St of the spacing S between the inner surface of the displacement allowing hole and the connecting shaft <NUM> (Gt > St).

Therefore, even in a case where an excessive load is applied to the connecting shaft <NUM>, the connecting shaft <NUM> comes into contact with the inner surface of the displacement allowing hole. Therefore, the interlocking member <NUM> does not come into contact with the upper surface 65B of the second horizontal plate portion 62B.

Incidentally, in a case where the displacement restricting portion <NUM> has a curved surface that curves toward the upper surface 65B of the horizontal plate portion 62B at the tilt position, the displacement restricting portion <NUM> is brought into point contact with the upper surface 65B of the horizontal plate portion 62B, and thus the pressure in the contact portion may become excessive.

On the other hand, in the present embodiment, as shown in <FIG>, the displacement restricting portion <NUM> has the flat surface P2 along the upper surface 65B of the horizontal plate portion 62B at the tilt position. Therefore, at the tilt position, the displacement restricting portion <NUM> and the upper surface 65B of the horizontal plate portion 62B are in contact with each other between the flat surfaces. Therefore, it is possible to prevent the pressure at the contact portion from becoming excessive.

In the present embodiment, the cab <NUM> is rotatable to a lift-up position inclined more than the tilt position, the displacement restricting portion <NUM> has the first restricting portion <NUM> that is in contact with the upper surface 65B of the horizontal plate portion 62B at the tilt position, and the second restricting portion <NUM> that is in contact with the upper surface 65B of the horizontal plate portion 62B at the lift-up position, and the second restricting portion <NUM> has the arc-shaped curved surface P3 that curves outward in the radial direction of the connecting shaft <NUM> when viewed in an axial direction along the connecting shaft <NUM>.

Therefore, it is possible to smoothly switch from the tilt position to the lift-up position by rotating the interlocking member <NUM>.

Incidentally, in a case where the second restricting portion <NUM> has a square shape projecting outward in the radial direction of the connecting shaft <NUM> when viewed in the axial direction, the connecting shaft <NUM> may be excessively displaced in the direction of arrow F (upward) shown in <FIG>, and an excessive upward load may be applied to the mount device <NUM>.

On the other hand, in the present embodiment, the second restricting portion <NUM> has the arc-shaped curved surface P3 that curves outward in the radial direction of the connecting shaft <NUM> when viewed in the axial direction, and thus it is possible to prevent the connecting shaft <NUM> from being excessively displaced upward. Therefore, it is possible to prevent an excessive upward load from being applied to the mount device <NUM>.

In the present embodiment, the rear side support structure 29B further includes the cover <NUM> that is provided on the connecting mechanism <NUM> and covers the gap G.

Therefore, it is possible to prevent foreign matter such as gravel from entering the gap G.

In the present embodiment, the cover <NUM> is formed of an elastic material.

Therefore, the cover <NUM> can be deformed to follow the rotation of the interlocking member <NUM> between the seated position and the tilt position. As a result, it is not necessary to attach and detach the cover <NUM> to and from the connecting mechanism <NUM>, and thus it is possible to enhance the workability.

In the present embodiment, each of the displacement allowing members 60A and 60B and the interlocking member <NUM> is formed of a material of a hardened metal.

Therefore, it is possible to increase the strength of each of the displacement allowing members 60A and 60B and the interlocking member <NUM> and to curb wear thereof compared to the case where at least one of the displacement allowing members 60A and 60B and the interlocking member <NUM> is formed of a simple metal (a material of not hardened metal).

In the present embodiment, a pair of displacement allowing members 60A and 60B are provided, and the pair of displacement allowing members 60A and 60B are a first displacement allowing member 60A provided on a first end side of the connecting shaft <NUM> in an axial direction and a second displacement allowing member 60B provided on a second end side of the connecting shaft <NUM> in the axial direction.

Therefore, even in a case where an excessive load is applied to the connecting shaft <NUM>, the connecting shaft <NUM> comes into contact with the inner surfaces of the displacement allowing holes 63A and 63B in the first displacement allowing member 60A and the second displacement allowing member 60B. Therefore, the interlocking member <NUM> does not come into contact with the upper surface 65B of the second horizontal plate portion 62B.

Incidentally, when the displacement allowing member is connected to the front frame <NUM>, it is necessary to the work of lifting the displacement allowing member above the front frame <NUM>. If the displacement allowing member is a single member, the weight of the displacement allowing member is heavy, which may make the work of lifting the displacement allowing member difficult.

On the other hand, in the present embodiment, a pair of displacement allowing members 60A and 60B are provided, and thus the displacement allowing members 60A and 60B can share the weight. Therefore, it is possible to facilitate the work of lifting the displacement allowing members 60A and 60B.

In the present embodiment, the rear side support structure 29B further includes the cab side bracket <NUM> connected to the cab <NUM>. The cab side bracket <NUM> has the cab side attachment hole <NUM> through which the connecting shaft <NUM> is inserted, and the interlocking member <NUM> is connected to the cab <NUM> via the cab side bracket <NUM>.

Since the interlocking member <NUM> is connected to the cab <NUM> via the connecting shaft <NUM> and the cab side bracket <NUM>, it is possible to more firmly connect the interlocking member <NUM> to the cab <NUM>. Therefore, the interlocking member <NUM> can be rotated more smoothly in interlock with the rotation of the cab <NUM>.

In the above-described present embodiment, an example in which the displacement allowing portion <NUM> and the displacement restricting portion <NUM> are continuous along the outer periphery of the interlocking member <NUM> has been described, but the present invention is not limited to this. For example, the displacement allowing portion <NUM> and the displacement restricting portion <NUM> may not be continuous along the outer periphery of the interlocking member <NUM>. For example, at least one of the displacement allowing portion <NUM> and the displacement restricting portion <NUM> may be provided at a location different from the outer circumference of the interlocking member <NUM>. For example, the aspects of the displacement allowing portion <NUM> and the displacement restricting portion <NUM> can be changed according to the required specifications.

In the above-described embodiment, an example in which the gap G is provided between the displacement allowing portion <NUM> of the interlocking member <NUM> and the upper surface 65B of the horizontal plate portion 62B to allow the displacement of the connecting shaft <NUM> in the vertical direction at the seated position and the displacement restricting portion <NUM> of the interlocking member <NUM> is in contact with the upper surface 65B of the horizontal plate portion 62B at the tilt position has been described, but the present invention is not limited to this. For example, the gap G may be provided between the displacement allowing portion <NUM> of the interlocking member <NUM> and the upper surface of the front frame <NUM> to allow the displacement of the connecting shaft <NUM> in the vertical direction at the seated position, and the displacement restricting portion <NUM> of the interlocking member <NUM> may be in contact with the upper surface of the front frame <NUM> at the tilt position. For example, the displacement allowing members 60A and 60B may not have the horizontal plate portions 62A and 62B. For example, the aspects of the displacement allowing members 60A and 60B can be changed according to the required specifications.

In the above-described embodiment, an example in which the vertical dimension Gt of the gap G is larger than the vertical dimension St of the spacing S between the inner surface of the displacement allowing hole and the connecting shaft <NUM> (Gt > St) at the seated position has been described, but the present invention is not limited to this. For example, at the seated position, the vertical dimension Gt of the gap G may be equal to or smaller than the vertical dimension St of the spacing S between the inner surface of the displacement allowing hole and the connecting shaft <NUM> (Gt ≤ St).

In the above-described embodiment, an example in which the displacement restricting portion <NUM> has the flat surface P2 along the upper surface 65B of the horizontal plate portion 62B at the tilt position has been described, but the present invention is not limited to this. For example, the displacement restricting portion <NUM> may have a curved surface that curves toward the upper surface 65B of the horizontal plate portion 62B or a protrusion that protrudes toward the upper surface 65B of the horizontal plate portion 62B at the tilt position. For example, the shape of the displacement restricting portion <NUM> can be changed according to the required specifications.

In the above-described embodiment, an example in which the cab <NUM> is rotatable to a lift-up position inclined more than the tilt position, the displacement restricting portion <NUM> has the first restricting portion <NUM> that is in contact with the upper surface 65B of the horizontal plate portion 62B at the tilt position, and the second restricting portion <NUM> that is in contact with the upper surface 65B of the horizontal plate portion 62B at the lift-up position, and the second restricting portion <NUM> has the arc-shaped curved surface P3 that curves outward in the radial direction of the connecting shaft <NUM> when viewed in an axial direction along the connecting shaft <NUM> has been described, but the present invention is not limited to this. For example, the second restricting portion <NUM> may have an angular shape protruding outward in the radial direction of the connecting shaft <NUM> when viewed in the axial direction. For example, the shape of the second restricting portion <NUM> can be changed according to the required specifications.

In the above-described embodiment, an example in which the rear side support structure 29B further includes the cover <NUM> that is provided on the connecting mechanism <NUM> and covers the gap G has been described, but the present invention is not limited to this. For example, the rear side support structure 29B may not include the cover <NUM>. For example, the gap G may be exposed at all times.

In the above-described embodiment, an example in which the cover <NUM> is formed of an elastic material has been described, but the present invention is not limited to this. For example, the cover <NUM> may be formed of a material other than the elastic material. For example, the material forming the cover <NUM> can be changed according to the required specifications.

In the above-described embodiment, an example in which each of the displacement allowing members 60A and 60B and the interlocking member <NUM> is formed of a material of a hardened metal has been described, but the present invention is not limited to this. For example, at least one of the displacement allowing members 60A and 60B and the interlocking member <NUM> may be formed of a material of a hardened metal.

For example, in a case where the displacement allowing member 60B is detachably connected to the front frame <NUM> and the interlocking member <NUM> is detachably connected to the cab <NUM>, only the interlocking member <NUM> of the displacement allowing member 60B and the interlocking member <NUM> may be formed of a material of a hardened metal. In this case, it is possible to increase the strength of the interlocking member <NUM> and to curb the wear thereof. For example, in a case where replacement of the displacement allowing member 60B is easier than replacement of the interlocking member <NUM>, it is possible to facilitate the work of replacing the displacement allowing member 60B with a new displacement allowing member when the displacement allowing member 60B is worn while the frequency of replacement of the interlocking member <NUM> is reduced.

In the above-described embodiment, an example in which a pair of displacement allowing members 60A and 60B are provided, and the pair of displacement allowing members 60A and 60B are the first displacement allowing member 60A provided on a first end side of the connecting shaft <NUM> in an axial direction and the second displacement allowing member 60B provided on a second end side of the connecting shaft <NUM> in the axial direction has been described, but the present invention is not limited to this. For example, the displacement allowing member may be a single member. For example, the aspect of the displacement allowing member can be changed according to the required specifications.

In the present embodiment, an example in which the rear side support structure 29B further includes the cab side bracket <NUM> connected to the cab <NUM> and the cab side bracket <NUM> has the cab side attachment hole <NUM> through which the connecting shaft <NUM> is inserted, and the interlocking member <NUM> is connected to the cab <NUM> via the cab side bracket <NUM> has been described, but the present invention is not limited to this. For example, the rear side support structure 29B may not include the cab side bracket <NUM>. For example, the interlocking member <NUM> may be connected to the cab <NUM> via the connecting shaft <NUM> without the cab side bracket <NUM>. For example, the connection aspect of the interlocking member <NUM> can be changed according to the required specifications.

In the above-described embodiment, the articulated dump truck <NUM> in which the vehicle body frame is constituted by the front frame and the rear frame has been described as an example of the construction machine (the work vehicle), but the present invention is not limited to this. For example, the present invention may be applied to other work vehicles such as a rigid frame dump truck having a single vehicle body frame, a hydraulic excavator, and a bulldozer.

Claim 1:
A cab support structure (29B) of a construction machine (<NUM>) comprising:
a mount device (<NUM>) to be provided on a vehicle body frame (<NUM>); and
a connecting mechanism (<NUM>) that is configured to connect a cab (<NUM>) provided above the vehicle body frame (<NUM>) via the mount device (<NUM>) to the vehicle body frame (<NUM>) to be rotatable between a seated position and a tilt position,
wherein the connecting mechanism (<NUM>) includes
a connecting shaft (<NUM>) that is connected to the mount device (<NUM>) and extends in a horizontal direction in a state where the construction machine (<NUM>) is disposed on a horizontal plane,
a displacement allowing member (60A, 60B) configured to be connected to the vehicle body frame (<NUM>), and
an interlocking member (<NUM>) that is configured to be connected to the cab (<NUM>) and is rotatable in interlock with rotation of the cab (<NUM>),
characterised in that, the displacement allowing member (60A, 60B) has a displacement allowing hole (63B) that allows displacement of the connecting shaft (<NUM>) in a vertical direction and allows rotation of the connecting shaft (<NUM>) between the seated position and the tilt position, and
wherein the interlocking member (<NUM>) has
a displacement allowing portion (<NUM>) that allows displacement of the connecting shaft (<NUM>) in the vertical direction at the seated position, and
a displacement restricting portion (<NUM>) that restricts downward displacement of the connecting shaft (<NUM>) at the tilt position.