Suspension mechanism for reel mowers

Claim 2

A mower, comprising: a reel mower cutting unit having front and rear portions, and a center of gravity, and front and rear support means for supporting the cutting unit on the ground during mowing operation, an arm pivotally coupled with the cutting unit at a pivotal connection point, said pivotal connection point being located to the rear of the cutting unit's center of gravity and above the front and rear support means for generally equalizing the force transmitted to the ground by the front and rear support means during forward travel.

Claim 3

The invention of claim 1, and further comprising a downforce applying means operatively coupled with the arm for applying a downward force to the cutting unit during operation.

Claim 4

The invention of claim 2, wherein the location of the pivotal connection point above the front and rear support means causes the front portion of the cutting unit to press downwardly against the ground due to ground resistance during forward travel, and the location of the pivotal connection point through which the downward force is applied to the cutting unit is behind the cutting unit's center of gravity for applying a greater portion of the downforce to the rear support means than the front support means for generally equalizing the amount of force applied to the ground by the front and rear support means during forward travel and thereby generally counteracting the tendency of the front portion to dip.

Claim 5

The invention of claim 3, wherein the front and rear supports are each transversely extending rollers.

Claim 6

The invention of claim 4, and further including a side frame positioned at a lateral edge portion of the cutting unit, said pivotal connection point being coupled directly to the side frame.

Claim 7

The invention of claim 1, wherein the pivotal connection point is located at an upper rear quadrant of the side frame.

Claim 8

A reel mower suspension mechanism for use with a vehicle, comprising: a reel mower cutting unit having front and rear portions, said cutting unit including: at least one side frame, a ground engaging front roller coupled with the front portion of the cutting unit for generally supporting the front portion of the cutting unit during mowing operation, a ground engaging rear roller coupled with the rear portion of the cutting unit for generally supporting the rear portion of the cutting unit during mowing operation, and an arm coupled with the vehicle and operatively coupled with the side frame of the cutting unit at a pivotal connection point, said pivotal connection point being located to the rear of the cutting unit's center of gravity and above the front and rear rollers for generally equalizing the force transmitted to the ground by the front and rear support means during forward travel of the vehicle and cutting unit, thereby reducing the tendency of the front portion of the cutting unit to dip during forward travel.

Claim 9

A reel mower suspension mechanism for use with a vehicle, comprising: a reel mower cutting unit having front and rear portions, said cutting unit including: at least one side frame, a ground engaging front roller coupled with the front portion of the cutting unit for generally supporting the front portion of the cutting unit during mowing operation, a ground engaging rear roller coupled with the rear portion of the cutting unit for generally supporting the rear portion of the cutting unit during mowing operation, and an arm coupled with the vehicle and operatively coupled with the side frame of the cutting unit at a pivotal connection point, said pivotal connection point being located to the rear of the cutting unit's center of gravity and above the front and rear rollers for generally equalizing the force transmitted to the ground by the front and rear support means during forward travel of the vehicle and cutting unit, thereby reducing the tendency of the front portion of the cutting unit to dip during forward travel.

Claim 10

The invention of claim 7, wherein the pivotal connection point is coupled with an upper rear quadrant of the side frame.

Claim 11

The invention of claim 7, wherein the pivotal connection point is located beneath a top edge of the side frame.

Claim 12

The invention of claim 7, wherein the cutting unit further includes a pair of side frames laterally spaced from each other, a yoke is pivotally coupled with each side frame of the cutting unit, and respective pivotal connection points couple each side frame with the yoke, and said arm is coupled between the vehicle and the yoke for propelling the cutting unit with the vehicle.

Claim 13

The invention of claim 10, wherein the yoke is pulled by the arm during forward vehicle travel.

Claim 14

The invention of claim 7, and further comprising a downforce applying means operatively coupled with the arm for applying a downward force to the cutting unit during operation.

Claim 15

A reel mower suspension mechanism for use with a vehicle, comprising: a reel mower cutting unit having front and rear portions, said cutting unit including: a pair of laterally spaced side frames, a ground engaging front roller coupled with the front portion of the cutting unit for generally supporting the front portion of the cutting unit during mowing operation, a ground engaging rear roller coupled with the rear portion of the cutting unit for generally supporting the rear portion of the cutting unit during mowing operation, and an arm means coupled with the vehicle, a yoke means operatively connected between each side frame and the arm means for operatively coupling the cutting unit with the vehicle, a downward force being applied to the cutting unit via said yoke and arm means, and said yoke being pivotally coupled with the cutting unit at a location closer to the rear roller than the front roller for transmitting a greater portion of the downward force to the rear roller than the front roller and generally equalizing the weight carried by the front and rear rollers during forward travel for reducing the tendency of the front portion of the cutting unit to dip during forward travel.

Claim 16

A reel mower suspension mechanism for use with a vehicle, comprising: a reel mower cutting unit having front and rear portions, said cutting unit including: a pair of laterally spaced side frames, a ground engaging front roller coupled with the front portion of the cutting unit for generally supporting the front portion of the cutting unit during mowing operation, a ground engaging rear roller coupled with the rear portion of the cutting unit for generally supporting the rear portion of the cutting unit during mowing operation, and an arm means coupled with the vehicle, a yoke means operatively connected between each side frame and the arm means for operatively coupling the cutting unit with the vehicle, a downward force being applied to the cutting unit via said yoke and arm means, and said yoke being pivotally coupled with the cutting unit at a location closer to the rear roller than the front roller for transmitting a greater portion of the downward force to the rear roller than the front roller and generally equalizing the weight carried by the front and rear rollers during forward travel for reducing the tendency of the front portion of the cutting unit to dip during forward travel.

Claim 17

The invention of claim 13, wherein the yoke means is coupled directly to an upper rear quadrant of each side frame.

Claim 18

A mower mechanism couplable to a vehicle, comprising: an arm means pivotally coupled with the vehicle, a reel mower cutting unit having an underside which must be accessed for service, said cutting unit being operatively coupled with the arm means for being propelled with the vehicle, said arm means being pivotal to raise the reel mower off the ground to a service position, a yoke coupled between the cutting unit and the arm means, said cutting unit being generally pivotal with respect to the yoke, a member coupled with the cutting unit for maintaining the cutting unit in generally horizontal position when the arm means is raised to a transport position, and first releasable locking means for generally securing the yoke against excessive pivoting with respect to the arm means during mowing operations, said first locking means being releasable to allow the yoke to pivot downwardly with respect to the arm means when the arm means is raised to a service position for exposing the underside of the cutting unit for service.

Claim 19

A mower mechanism couplable to a vehicle, comprising: an arm means pivotally coupled with the vehicle, a reel mower cutting unit having an underside which must be accessed for service, said cutting unit being operatively coupled with the arm means for being propelled with the vehicle, said arm means being pivotal to raise the reel mower off the ground to a service position, a yoke coupled between the cutting unit and the arm means, said cutting unit being generally pivotal with respect to the yoke, a member coupled with the cutting unit for maintaining the cutting unit in generally horizontal position when the arm means is raised to a transport position, and first releasable locking means for generally securing the yoke against excessive pivoting with respect to the arm means during mowing operations, said first locking means being releasable to allow the yoke to pivot downwardly with respect to the arm means when the arm means is raised to a service position for exposing the underside of the cutting unit for service.

Claim 20

The invention of claim 15, and further including a second releasable locking means which restricts excessive pivoting of the yoke about a generally vertical axis with respect to the arm means during mowing operation, said second locking means being releasable for allowing the yoke to pivot to expose the underside of the cutting unit laterally outwardly from the vehicle when the arm means is raised to its service position.

Claim 21

The invention of claim 15, wherein the yoke is coupled to the rear of the center of gravity of the cutting unit.

Claim 22

The invention of claim 17, wherein the member prevents the cutting unit from pivoting downwardly with respect to the yoke when the arm is raised to the service position.

Claim 23

The invention of claim 17, and further comprising front and rear ground engaging rollers, said yoke being coupled to the cutting unit at a location closer to the rear ground engaging roller than the front ground engaging roller.

Claim 24

The invention of claim 19, wherein the member extends between the cutting unit and yoke for preventing the cutting unit from pivoting dowardly with respect to the yoke when the arm is raised to the service position.

Claim 25

The invention of claim 19, wherein the member extends between the cutting unit and yoke for preventing the cutting unit from pivoting downwardly with respect to the yoke when the arm is raised to the service position.

Claim 26

A mower mechanism couplable to a vehicle, comprising: an arm means pivotally coupled with the vehicle, a reel mower cutting unit having an underside which must be accessed for service, said cutting unit being operatively coupled with the arm means for being propelled with the vehicle, said arm means being pivotal to raise the reel mower off the ground to a service position, a yoke coupled between the cutting unit and the arm means, said yoke being coupled to the rear of the center of gravity of the cutting unit, and said cutting unit being generally pivotal with respect to the yoke, a member coupled with the cutting unit for maintaining the cutting unit in generally horizontal position when the arm means is raised to a transport position, wherein the member generally prevents the cutting unit from pivoting downwardly with respect to the yoke when the arm is raised to a service position, first releasable locking means for generally securing the yoke against excessive pivoting with respect to the arm means during mowing operations, said first locking means being releasable to allow the yoke to pivot downwardly with respect to the arm means when the arm means is raised to a service position for exposing the underside of the cutting unit for service.

Claim 27

A mower mechanism couplable to a vehicle, comprising: an arm means pivotally coupled with the vehicle, a reel mower cutting unit having an underside which must be accessed for service, said cutting unit being operatively coupled with the arm means for being propelled with the vehicle, said arm means being pivotal to raise the reel mower off the ground to a service position, a yoke coupled between the cutting unit and the arm means, said yoke being coupled to the rear of the center of gravity of the cutting unit, and said cutting unit being generally pivotal with respect to the yoke, a member coupled with the cutting unit for maintaining the cutting unit in generally horizontal position when the arm means is raised to a transport position, wherein the member generally prevents the cutting unit from pivoting downwardly with respect to the yoke when the arm is raised to a service position, first releasable locking means for generally securing the yoke against excessive pivoting with respect to the arm means during mowing operations, said first locking means being releasable to allow the yoke to pivot downwardly with respect to the arm means when the arm means is raised to a service position for exposing the underside of the cutting unit for service.

Claim 28

The invention of claim 22, and further including a second releasable locking means which restricts excessive pivoting of the yoke about a generally vertical axis with respect to the arm means during mowing operation, said second locking means being releasable for allowing the yoke to pivot to expose the underside of the cutting unit laterally outwardly from the vehicle when the arm means is raised to its service position.

Claim 29

The invention of claim 23, and further comprising front and rear ground engaging rollers, said yoke being coupled to the cutting unit at a location closer to the rear ground engaging roller than the front ground engaging roller.

Claim 30

A mower mechanism couplable to a vehicle, comprising: an arm means pivotally coupled with the vehicle, a reel mower cutting unit having an underside which must be accessed for service, said cutting unit being operatively coupled with the arm means for being propelled with the vehicle, said arm means being pivotal to raise the reel mower off the ground to a transport position and a service position, and a releasable member coupled with the cutting unit for maintaining the cutting unit in generally horizontal position when the arm means is raised to the transport position, said member being releasable to allow the cutting unit to swing downwardly with respect to the arm means to expose the underside of the cutting unit for service when said arm means is raised to the service position.

Claim 31

A mower mechanism couplable to a vehicle, comprising: an arm means pivotally coupled with the vehicle, a reel mower cutting unit having an underside which must be accessed for service, said cutting unit being operatively coupled with the arm means for being propelled with the vehicle, said arm means being pivotal to raise the reel mower off the ground to a transport position and a service position, and a releasable member coupled with the cutting unit for maintaining the cutting unit in generally horizontal position when the arm means is raised to the transport position, said member being releasable to allow the cutting unit to swing downwardly with respect to the arm means to expose the underside of the cutting unit for service when said arm means is raised to the service position.

Claim 32

A reel mower including a main frame, an arm means vertically pivotally mounted to the main frame and a trailing link coupled to an end of the arm means, and a cutting unit having a frame supporting a reel and bed knife between front and rear rollers having a connection with the trailing link permitting vertical pivotal movement of the cutting unit about a horizontal axis extending cross wise to the direction of travel of the cutting unit, the improvement comprising: the connection of the arm member with the cutting unit being located at a first location on the cutting unit; and a lift element releasably connected between the lift arm and the cutting unit at a second location spaced from said first location so that the lift element maintains the cutting unit in a generally level attitude when lifted by raising the lift arm while the lift element is installed but permits the cutting unit to pivot at said connection to assume a position exposing said reel, bed knife and front and rear rollers when said lift element is released.

Claim 33

A reel mower including a main frame, an arm means vertically pivotally mounted to the main frame and a trailing link coupled to an end of the arm means, and a cutting unit having a frame supporting a reel and bed knife between front and rear rollers having a connection with the trailing link permitting vertical pivotal movement of the cutting unit about a horizontal axis extending cross wise to the direction of travel of the cutting unit, the improvement comprising: the connection of the arm member with the cutting unit being located at a first location on the cutting unit; and a lift element releasably connected between the lift arm and the cutting unit at a second location spaced from said first location so that the lift element maintains the cutting unit in a generally level attitude when lifted by raising the lift arm while the lift element is installed but permits the cutting unit to pivot at said connection to assume a position exposing said reel, bed knife and front and rear rollers when said lift element is released.

Claim 34

The reel mower defined in claim 26, wherein said connection includes a first pivot means for establishing a generally horizontal, fore-and-aft extending axis about which said trailing link and cutting unit may pivot.

Claim 35

The reel mower defined in claim 26 wherein said trailing link is in the form of a yoke having opposite ends pivotally attached to the cutting unit frame and having a central location between the opposite ends coupled to said lift arm.

Claim 36

The reel mower defined in claim 28 wherein said central location of the yoke is defined by a cylindrical tubular receptacle which extends in the direction of travel; and said connection including a coupling pin received in said receptacle whereby the yoke and cutting unit may pivot about said coupling pin.

Claim 37

A reel mower including a main frame, an arm means vertically pivotally mounted to the main frame and a trailing link coupled to an end of the lift arm, and a cutting unit having a frame supporting a reel and bed knife between front and rear rollers having a connection with the trailing link permitting vertical pivotal movement of the cutting unit about a horizontal axis extending cross wise to the direction of travel of the cutting unit, the improvement comprising: the connection with the cutting unit being located at a forward location of the cutting unit; and a lift element releasably connected between the lift arm and the cutting unit at a second location spaced rearwardly of said forward location so that the lift element maintains the cutting unit in a generally level attitude when lifted by raising the lift arm while the lift element is installed but permits the cutting unit to pivot at said connection to assume a position exposing said reel, bed knife and front and rear rollers when said lift element is released.

Claim 38

A reel mower including a main frame, an arm means vertically pivotally mounted to the main frame and a trailing link coupled to an end of the lift arm, and a cutting unit having a frame supporting a reel and bed knife between front and rear rollers having a connection with the trailing link permitting vertical pivotal movement of the cutting unit about a horizontal axis extending cross wise to the direction of travel of the cutting unit, the improvement comprising: the connection with the cutting unit being located at a forward location of the cutting unit; and a lift element releasably connected between the lift arm and the cutting unit at a second location spaced rearwardly of said forward location so that the lift element maintains the cutting unit in a generally level attitude when lifted by raising the lift arm while the lift element is installed but permits the cutting unit to pivot at said connection to assume a position exposing said reel, bed knife and front and rear rollers when said lift element is released.

Claim 39

The reel mower as defined in claim 30 wherein the lift arm is located such that the cutting unit has a least a portion extending beneath said main frame when the cutting unit is in a lowered working position and such that said arm end is positioned outwardly of said main frame; and said connection defining a substantially upright axis about which the cutting unit may be pivoted to a position disposing the entire cutting unit frame outwardly of the main mower frame, whereby removal of the lifting element and lifting of the cutting unit through means of the arm and link will result in the bottom of the cutting unit being exposed for permitting a technician to check the height of cut and bed knife to reel clearance.

Claim 40

A mower mechanism couplable to a vehicle, comprising: an arm means pivotally coupled with the vehicle, a reel mower cutting unit having an underside which must be accessed for service, said cutting unit being operatively coupled with the arm means for being propelled with the vehicle, said arm means for being pivotal to raise the reel mower off the ground to a transport position and a service position, and a releasable member coupled with the cutting unit for maintaining the cutting unit in generally horizontal position when the arm means is raised to the transport position, said member being releasable to allow the cutting unit to swing downwardly with respect to the arm means to expose the underside of the cutting unit for service when said arm means is raised to the service position, a yoke which couples the cutting unit with the arm means, said cutting unit being generally pivotal with respect to the yoke, and a releasable locking means which restricts the yoke from pivoting about a vertical axis during mowing operation, said locking means being releasable for allowing the yoke to pivot to expose the underside of the cutting unit laterally outwardly from the vehicle for service.

Claim 41

A mower mechanism couplable to a vehicle, comprising: an arm means pivotally coupled with the vehicle, a reel mower cutting unit having an underside which must be accessed for service, said cutting unit being operatively coupled with the arm means for being propelled with the vehicle, said arm means for being pivotal to raise the reel mower off the ground to a transport position and a service position, and a releasable member coupled with the cutting unit for maintaining the cutting unit in generally horizontal position when the arm means is raised to the transport position, said member being releasable to allow the cutting unit to swing downwardly with respect to the arm means to expose the underside of the cutting unit for service when said arm means is raised to the service position, a yoke which couples the cutting unit with the arm means, said cutting unit being generally pivotal with respect to the yoke, and a releasable locking means which restricts the yoke from pivoting about a vertical axis during mowing operation, said locking means being releasable for allowing the yoke to pivot to expose the underside of the cutting unit laterally outwardly from the vehicle for service.

Claim 42

A reel mower including a main frame, an arm means vertically pivotally mounted to the main frame and a trailing link coupled to an end of the arm means, and a cutting unit having a frame supporting a reel and bed knife between front and rear rollers having a connection with the trailing link permitting vertical pivotal movement of the cutting unit about a horizontal axis extending cross wise to the direction of travel of the cutting unit, the improvement comprising: the connection of the arm member with the cutting unit being located at a first location on the cutting unit; and a lift element being releasably connected between the lift arm and the cutting unit at a second location spaced from said first location so that the lift element maintains the cutting unit in a generally level attitude when lifted by raising the lift arm while the lift element is installed but permits the cutting unit to pivot at said connection to assume a position exposing said reel, bed knife and front and rear rollers when said lift element is released, wherein said connection includes a first pivot means for establishing a generally horizontal, fore-and-aft extending axis about which said trailing link and cutting unit may pivot, and said connection includes a second pivot means for establishing a generally upright pivot axis about which said trailing link and cutting unit may pivot.

Claim 43

A reel mower including a main frame, an arm means vertically pivotally mounted to the main frame and a trailing link coupled to an end of the arm means, and a cutting unit having a frame supporting a reel and bed knife between front and rear rollers having a connection with the trailing link permitting vertical pivotal movement of the cutting unit about a horizontal axis extending cross wise to the direction of travel of the cutting unit, the improvement comprising: the connection of the arm member with the cutting unit being located at a first location on the cutting unit; and a lift element being releasably connected between the lift arm and the cutting unit at a second location spaced from said first location so that the lift element maintains the cutting unit in a generally level attitude when lifted by raising the lift arm while the lift element is installed but permits the cutting unit to pivot at said connection to assume a position exposing said reel, bed knife and front and rear rollers when said lift element is released, wherein said connection includes a first pivot means for establishing a generally horizontal, fore-and-aft extending axis about which said trailing link and cutting unit may pivot, and said connection includes a second pivot means for establishing a generally upright pivot axis about which said trailing link and cutting unit may pivot.

Claim 44

A reel mower including a main frame, an arm means vertically pivotally mounted to the main frame and a trailing link coupled to an end of the arm means, and a cutting unit having a frame supporting a reel and bed knife between front and rear rollers having a connection with the trailing link permitting vertical pivotal movement of the cutting unit about a horizontal axis extending cross wise to the direction of travel of the cutting unit, the improvement comprising: the connection of the arm member with the cutting unit being located at a first location on the cutting unit; and a lift element being releasably connected between the lift arm and the cutting unit at a second location spaced from said first location so that the lift element maintains the cutting unit in a generally level attitude when lifted by raising the lift arm while the lift element is installed but permits the cutting unit to pivot at said connection to assume a position exposing said reel, bed knife and front and rear rollers when said lift element is released, wherein said trailing link is in the form of a yoke having opposite ends pivotally attached to the cutting unit frame and having a central location between the opposite ends coupled to said lift arm, wherein said central location of the yoke is defined by a cylindrical tubular receptacle which extends in the direction of travel; and said connection including a coupling pin received in said receptacle whereby the yoke and cutting unit may pivot about said coupling pin, and wherein said end of the arm is defined by a substantially upright tubular receptacle, and said connection including a v-shaped coupling pin having respective limbs received in said receptacles of the yoke and arm.

Claim 45

A reel mower including a main frame, an arm means vertically pivotally mounted to the main frame and a trailing link coupled to an end of the arm means, and a cutting unit having a frame supporting a reel and bed knife between front and rear rollers having a connection with the trailing link permitting vertical pivotal movement of the cutting unit about a horizontal axis extending cross wise to the direction of travel of the cutting unit, the improvement comprising: the connection of the arm member with the cutting unit being located at a first location on the cutting unit; and a lift element being releasably connected between the lift arm and the cutting unit at a second location spaced from said first location so that the lift element maintains the cutting unit in a generally level attitude when lifted by raising the lift arm while the lift element is installed but permits the cutting unit to pivot at said connection to assume a position exposing said reel, bed knife and front and rear rollers when said lift element is released, wherein said trailing link is in the form of a yoke having opposite ends pivotally attached to the cutting unit frame and having a central location between the opposite ends coupled to said lift arm, wherein said central location of the yoke is defined by a cylindrical tubular receptacle which extends in the direction of travel; and said connection including a coupling pin received in said receptacle whereby the yoke and cutting unit may pivot about said coupling pin, and wherein said end of the arm is defined by a substantially upright tubular receptacle, and said connection including a v-shaped coupling pin having respective limbs received in said receptacles of the yoke and arm.

Claim 46

A reel mower including a main frame, an arm means vertically pivotally mounted to the main frame and a trailing link coupled to an end of the arm means, and a cutting unit having a frame supporting a reel and bed knife between front and rear rollers having a connection with the trailing link permitting vertical pivotal movement of the cutting unit about a horizontal axis extending cross wise to the direction of travel of the cutting unit, the improvement comprising: the connection of the arm member with the cutting unit being located at a first location on the cutting unit; and a lift element being releasably connected between the lift arm and the cutting unit at a second location spaced from said first location so that the lift element maintains the cutting unit in a generally level attitude when lifted by raising the lift arm while the lift element is installed but permits the cutting unit to pivot at said connection to assume a position exposing said reel, bed knife and front and rear rollers when said lift element is released, wherein said trailing link is in the form of a yoke having opposite ends pivotally attached to the cutting unit frame and having a central location between the opposite ends coupled to said lift arm, wherein said central location of the yoke is defined by a cylindrical tubular receptacle which extends in the direction of travel; and said connection including a coupling pin received in said receptacle whereby the yoke and cutting unit may pivot about said coupling pin, wherein said end of the arm is defined by a substantially upright tubular receptacle, and said connection including a v-shaped coupling pin having respective limbs received in said receptacles of the yoke and arm, and wherein said connection further includes a v-shaped strap having respective limbs received on the respective limbs of the v-shaped coupling pin such that one strap limb is located ahead of the yoke receptacle while the other strap limb is located below the arm receptacle; said other strap limb being provided with a turn limiting notch; and a stop pin being releasably mounted to the arm receptacle with a lower end portion of the stop pin being located within the notch, whereby engagement of the stop pin with said other strap limb will limit the relative pivotal movement of the cutting unit to the arm as determined by the shape of the notch.

Claim 47

A reel mower including a main frame, an arm means vertically pivotally mounted to the main frame and a trailing link coupled to an end of the arm means, and a cutting unit having a frame supporting a reel and bed knife between front and rear rollers having a connection with the trailing link permitting vertical pivotal movement of the cutting unit about a horizontal axis extending cross wise to the direction of travel of the cutting unit, the improvement comprising: the connection of the arm member with the cutting unit being located at a first location on the cutting unit; and a lift element being releasably connected between the lift arm and the cutting unit at a second location spaced from said first location so that the lift element maintains the cutting unit in a generally level attitude when lifted by raising the lift arm while the lift element is installed but permits the cutting unit to pivot at said connection to assume a position exposing said reel, bed knife and front and rear rollers when said lift element is released, wherein said trailing link is in the form of a yoke having opposite ends pivotally attached to the cutting unit frame and having a central location between the opposite ends coupled to said lift arm, wherein said central location of the yoke is defined by a cylindrical tubular receptacle which extends in the direction of travel; and said connection including a coupling pin received in said receptacle whereby the yoke and cutting unit may pivot about said coupling pin, wherein said end of the arm is defined by a substantially upright tubular receptacle, and said connection including a v-shaped coupling pin having respective limbs received in said receptacles of the yoke and arm, and wherein said connection further includes a v-shaped strap having respective limbs received on the respective limbs of the v-shaped coupling pin such that one strap limb is located ahead of the yoke receptacle while the other strap limb is located below the arm receptacle; said other strap limb being provided with a turn limiting notch; and a stop pin being releasably mounted to the arm receptacle with a lower end portion of the stop pin being located within the notch, whereby engagement of the stop pin with said other strap limb will limit the relative pivotal movement of the cutting unit to the arm as determined by the shape of the notch.