Closure fasteners – Bolts – Swinging and hooked end – multiple head
Reexamination Certificate
2002-09-25
2004-02-10
Lavinder, Jack (Department: 3683)
Closure fasteners
Bolts
Swinging and hooked end, multiple head
C292S218000, C296S190100
Reexamination Certificate
active
06688658
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention generally relates to a cab window lock system installed in a cab of a construction machine, and more particularly, to a cab window lock system for locking, at a desired position, a cab window such as a front window which is openable by pulling-up operation.
BACKGROUND ART
An openable front window is usually provided for, for instance, a cab of a construction machine, at the front part thereof, for viewing the state of operation being carried out with the front implements. A typical front window is designed to be retractable to its housing position, by pulling it once frontward, pulling it up and backward, and then moving it to the ceiling side of the cab.
Generally, this front window should be fixedly installed on the front side of the cab such that rain and dust cannot penetrate into the cab from outside when it is in service, and should be stably held at its housing position when it is opened. To this end, such a front window is conventionally provided with a lock mechanism of the bolt (lock pin) type such as disclosed in Japanese Patent Publication (KOKAI) Gazette No. 10-311061 (1998). This mechanism has lock pins which are disposed on both ends of the top portion of a window frame so as to be fittable in engagement holes defined on the front pillars of the cab etc. At the time of opening or closing the window, the window is unlocked or locked, by pulling out or inserting the lock pins of the lock system relative to the holes. This prior art lock mechanism includes a holding mechanism in which holding levers are automatically brought into engagement with a roller shaft of the window frame upon arrival of the window frame at its travel end when it is moved to its housing position so that the window frame is held so as not to move back from the housing position.
In place of the above lock-pin type lock mechanism, another lock mechanism is proposed in Japanese Patent Publication (KOKAI) Gazette No. 10-311062 (1998) according to which latches are provided so as to rotate into engagement with strikers fixedly mounted on a structure (the body of a cab). In this lock mechanism, strikers in the form of
(Japanese katakana letter “ko”) are secured to the body of a cab, while two plate members each having an engagement groove are attached through brackets to a movable window frame at its upper and lower positions so as to work and turn in cooperation. When these plate members are released from a fastened condition by one release lever, the opposed engagement grooves of the plate members are respectively opened to the strikers by virtue of the force of torsion springs, receiving the strikers in a biting manner so that the engagement grooves are brought into locking engagement with the strikers. For unlocking the window, the plate members are respectively turned by the release lever in the direction opposite to the turning direction adapted at the time of engagement so that disengagement is established.
Japanese Patent Publication (KOKAI) Gazette No. 8-312220 discloses a lock mechanism having one latch capable of engaging with a moveable member provided at a home position and another moveable member provided at a position to which a door is moved. This mechanism uses, in combination, lock grooves (notches) formed on a turnable lock plate so as to be oriented in two different directions and a lock releasing lever for restricting the turn of the lock plate. When opening or closing the sliding door, a handle is operated to release the lock plate from the restriction by the lock releasing lever, so that the lock grooves of the lock plate are disengaged from lock pieces as the door moves. Then, upon arrival of the door at its sliding end, the lock grooves come in contact with lock pieces provided at this position so that the door is locked.
However, the lock-pin type lock mechanism of Japanese Patent Publication No. 10-311061 has a problem in its operablility that the lock pins have to be positioned relative to the lock holes for insertion and have to be anchored in the lock holes by rotation in order to prevent them from coming off. In addition, it is necessary to provide a radial gap between each pin and each pin hole (i.e., lock hole) in order to facilitate the positioning of the lock pin relative to the pin hole for insertion. The front window chatters with vibration all the more for the gap, generating noise and causing wear of the pin hole which brings about further vibration.
Another disadvantage of the system of this publication is that it needs a lock mechanism for locking the front window at the fixed position and a holding mechanism for holding it at the housing position, these mechanisms being different in structure. This is because the direction of locking the front window is utterly different from the direction of holding it. Therefore, the locking operation and the unlocking operation differ from each other, which leads to poor operability.
The lock mechanism having a latch and disclosed in Japanese Patent Publication No. 10-311062 involves a complex structure in which two plate members which respectively have an engagement groove are vertically arranged in an opposed relationship and these plate members cooperate to open and close their engagement grooves. In addition, this lock mechanism effectively functions in locking a window in an upright condition but cannot provide good stability when it is applied to the window in other conditions.
The lock mechanism disclosed in Japanese Patent Publication No. 8-312220 is advantageous in that two-directional operation can be performed, but the arrangement disclosed in this publication is insufficient to lock or hold the window frame at its travel end by use of only one latch (lock plate), the window frame being movable while changing its posture from an upright condition to a horizontally lying condition. More concretely, two different functions are required in locking and holding the window frame which moves upward changing its posture from an upright condition to a horizontally lying condition, one being a function for locking the window so as to press the window frame against a support structure at the periphery of the window when the window frame is in its upright position, while the other being a function for supporting the window frame which is coming down because of gravity and holding it so as not to move back when the window frame is in its upper, housing position. There is a difficulty in adapting the latch mechanism disclosed in the above publication to a cab window which requires the above functions.
The present invention is directed to overcoming the foregoing problems. Therefore, a first object of the invention is to provide a cab window lock system which is simple in structure and enables stable, easy locking operation and unlocking operation.
A second object of the invention is to provide a cab window lock system capable of reliably closing and fixing a window of the lift open type at its closing position, and reliably holding and housing it at its upper housing position.
DISCLOSURE OF THE INVENTION
The first object of the invention can be achieved by a cab window lock system according to a first aspect of the invention.
This lock system is composed of lock mechanisms each comprising a turnable latch and a release lever for restricting the turn of the latch in its disengaging direction,
each of the lock mechanisms further comprising a release lever disengagement maintaining mechanism which comes into engagement with the release lever to keep the release lever in its disengaging condition at a disengaging position where the latch is disengaged from the release lever,
the release lever disengagement maintaining mechanism being designed to release the release lever from its disengaging condition when the latch has turned through a specified rotation angle.
According to the invention arranged as described above, if the release lever is operated to cancel the engagement between the latch and the release lever thereby unlocking the latch, the release lever disengagem
Mori Tadashi
Shioji Hiroyuki
Sogo Masanori
Armstrong, Kratz, Quintos Hanson & Brooks, LLP.
Komatsu Ltd.
Lavinder Jack
Williams Thomas J.
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