Harvesters – Motorized harvester – Having motor on ground-supported carrier
Reexamination Certificate
1999-07-09
2001-06-05
Pezzuto, Robert E. (Department: 3671)
Harvesters
Motorized harvester
Having motor on ground-supported carrier
C166S068000
Reexamination Certificate
active
06240713
ABSTRACT:
TECHNICAL FIELD
The present invention relates to lawn mowers and in particular to lawn mowers mounted on castor wheels.
DISCUSSION
A conventional lawn mower comprises a cutting deck mounted on four wheels. A motor, which can be either an electric motor or an internal combustion engine, is mounted on the cutting deck and which rotatingly drives a cutting blade mounted below the cutting deck about a substantially vertical axis of rotation. A handle is attached to the rear of the cutting deck to enable an operator to maneuver the mower. Often a grass collection box is also attached to the rear of the cutting deck to collect the grass cuttings generated by the mower when in use.
In common mower designs the wheels have a direction of travel which is fixed in a forward and rearward direction. Thus the mower is able to be pushed or pulled in a forward or rearward direction. This is particularly desirable when an operator wishes to operate the mower in straight lines, for instance to generate stripes on a lawn. However, such a design of mower is unable to change direction easily. In order for the direction of travel to be altered, the operator must raise either the front or rear wheels above the ground and rotate the mower to the new direction of travel before then lowering the wheels in order to re-engage the ground. This requires a substantial effort on the part of the operator. Furthermore, the direction of travel of the mower while cutting the grass still remains in a forward/rearward direction which may not be desirable in certain circumstances.
One known method of overcoming these problems is to mount the mower on castor wheels which are capable of swivelling freely through 360°. This enables the lawn mower to be maneuvered in any direction, in a forward/rearward direction, sideways, diagonally, rotationally etc. This makes the lawn mower highly maneuverable. Furthermore, it obviates the need for the operator to raise the wheels off the ground when he wishes to change direction. However, such maneuverability may not be desirable in certain circumstances. For instance, if an operator is using the mower on an inclined surface such as the side of a hill or bank and the operator wishes to traverse along the side of the hill or bank in a straight line with the mower, the operator would have to use considerable effort to maintain the direction of travel of the mower in a straight line and to prevent the mower from sliding sideways down the hill or bank.
It is therefore desirable to have a lawn mower which is able to be changed between two modes of operation, a first mode where the mower is able to move in any direction both linearly and rotationally (i.e. the wheels can freely swivel to any direction of travel), and a second mode where the mower is only able to move in one fixed direction of travel.
U.S. Pat. No. 5,653,096 discloses such a mower. The cutting deck of the mower is mounted on three castor wheels. In its first mode of operation, the castor wheels are able to swivel freely, thereby enabling the mower to be maneuvered in any direction. In its second mode of operation, the direction of travel of the two rear castor wheels of the mower can be locked in a forward/reverse direction or sideways direction. When the direction of travel of the two rear wheels is fixed, the mower is only able to travel in either a forward/reverse direction or a sideways direction.
The locking mechanism disclosed in U.S. Pat. No. 5,653,096 for each rear castor wheel comprises a locking pin mounted on the cutting deck close to the castor wheel. Corresponding holes, which are capable of receiving the locking pin, are formed in the castor wheel. In the first mode of operation the pin is held away from the holes. The castor wheel is able to freely swivel through 360?. However, when one of the holes in the castor wheel is aligned with the locking pin and the locking pin is moved such that it engages with the hole, the castor wheel is prevented from swivelling, its direction of travel being fixed. The direction of travel of the castor wheel is determined by the position of the hole on the castor wheel.
However, the locking mechanism disclosed in U.S. Pat. No. 5,653,096 suffers from a number of problems. Firstly, and most importantly, the direction of travel of the mower when in the second mode of operation is fixed to two predetermined directions, namely sideways and forward/reverse. In certain situations this is undesirable. The user may wish to push the lawn mower diagonally or at an angle and therefore would like to fix the direction of travel of the wheels in these particular directions. Furthermore, the operator may wish to fix the wheels in an orientation which enables the mower to move in an arc, so that it cuts the grass in a uniform manner around an object. This is not possible with the wheel alignment mechanism disclosed in U.S. Pat. No. 5,653,096. Secondly, the operator has to bend down in order to grasp the pin in order to either lock or unlock each of the castor wheels individually, which may cause discomfort for an operator who suffers from back problems. Furthermore, the operator is required to place his hands close to the cutting blade while locking or unlocking the castor wheel, thus putting the operator at unnecessary risk. Thirdly, as the direction of travel of the castor wheel must be fixed with some reasonable accuracy, the diameter of the hole must be similar to that of the pin. However, the castor wheels and hence the holes are located close to the zone swept out by the cutting blade when in use and, as such, would encounter grass cuttings and other debris generated by the cutting action of the mower. When the pins are held away from the holes to allow the wheels to freely swivel, then the holes are filled up with grass cuttings and/or debris, thus preventing the pins from being inserted into the holes. In such circumstances an operator may be likely to try and force the pin into the hole, which could be dangerous, particularly in view of the close proximity of the cutting blade to the castor wheel.
SUMMARY OF THE INVENTION
According to the present invention there is provided a lawn mower comprising a deck mounted on at least one castor wheel assembly characterized in that there is provided a locking mechanism capable of holding the at least one castor wheel assembly in the direction it was travelling when the braking mechanism is operated.
By constructing the lawn mower in such a manner, the lawn mower has the benefits that firstly it is able to operate in two different modes, namely a first mode where it is highly maneuverable and a second mode where the direction of travel of the castor wheels is fixed, secondly, the mower can easily be changed between the two modes of operation and thirdly, when the mower is used in the second mode of operation, the direction of travel of the castor wheels can be locked in any desired angular position.
The locking mechanism holds the castor wheel assembly and prevents it from swivelling about a substantially vertical axis. It will be clear to a person skilled in the art that it is within the scope of the invention that any known braking mechanism can be utilized to hold the castor wheel assembly such as, but not limited to, drum brakes, disk brakes, caliper brakes whether operated hydraulically, pneumatically, electrically or by mechanical means.
The cutting deck can be mounted on four castor wheel assemblies, at least two of which are provided with a locking mechanism.
One simple construction of such a locking mechanism comprises two parts, a first part mounted on the castor wheel assembly, a second part mounted on the deck, a braking surface formed on one part and a braking element mounted on the other part, the braking element being movable between a first position where the braking surface is rotatable relative to the braking element to allow the castor wheel assembly to swivel about a substantially vertical axis and a second position where the braking element engages and holds the braking surface.
The braking element can comprise a ba
Black & Decker Inc.
Harness & Dickey & Pierce P.L.C.
Kovács Arpád Fáb
Pezzuto Robert E.
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