Device for Fastening Ajar Door

The present invention relates to a device for fastening an ajar door, and more particularly, to a device for fastening an ajar door of an operator's cab.

Conventionally, an operator's cab having a device fastening the ajar door is constructed as in a perspective view shown in FIG. 6, and details of the device, indicated and are shown in the perspective view in FIG. 7, an elevational view in FIG. 8 and a top plan view in FIG. 9.

More specifically, a door 2 is swingably fixed to a side 3 of an operator's cab I by means of a hinge 4. A lock member 40 having a lock element 41 is fastened near the hinge 4 above the door 2 by means of a bolt 42. A bracket is attached to a position corresponding to the lock member 40 above the side 3, and a lock 50 is fastened by a bolt 55. The lock 50 includes a hook 51, a bracket 52, a pin 53 and a torsional spring 54 wherein the hook 51 is secured pivotally to the bracket 52 by means of the pin 53 and is urged in the direction of the arrow P (FIG. 8) by means of the torsional spring 54. The door is ajar and fastened by swinging the door 2 on the hinge 4 so as to allow the lock element 41 to push up the hook 51 against the urging force of the torsional spring 54 and to engage the hook 51 at the position indicated by chain double-dashed lines in FIGS. 8 and 9. The lock is unfastened by pushing up the hook 51 manually, thereby allowing the door 2 to close.

However, the foregoing construction has the following problems:

(1) Since the fastening device is fixed adjacent to the hinge of the door, the distance L.sub.2 (FIG. 9) between the center of the hinge and the center of the lock is small, and the lock is heavily burdened. Consequently, the fastening device has to be large and costly.

(2) Since the fastening device greatly protrudes at the top of the operator's cab, it might be damaged by obstacles and does not present a good appearance.

(3) Someone has to take the trouble to go out of the cab and release the lock manually to unfasten the ajar door, and this is operationally inconvenient.

In view of the foregoing problems, an object of the present invention is to provide a device for fastening the ajar door which device is small in size, presents a good appearance, and is easy to unfasten.

To this end, a device for fastening an ajar door comprises a plate support element fixed adjacent to the center of the hinge side of the outer surface of a door of an operator's cab, a tubular support element connected at one end to the plate support element and at the other end to the outer surface of the door, a U-shaped striker fixed to the plate support element, a lock fixed to the side wall of the operator's cab for holding the striker which moves together with the door when the door is ajar, and an unfastening lever for releasing the lock from inside the operator's cab. The tubular support element is three-dimensionally formed so that it will not block an operator's line of vision; the lock comprises a hook having an engaging surface, a pin securing the hook pivotally, and a spring urging the hook counterclockwise; and the unfastening lever comprises a stopper having an engaging surface at one end and a lever at the other end, a pin securing the stopper pivotally, and a spring urging the stopper clockwise. According to this construction, when the door is ajar, the fastening device holds the striker and keeps the door ajar. The fastening device is easily unfastened by operating the unfastening lever in the operator's cab. The advantages obtained from this are as follows:

(1) The distance L.sub.1 (FIG. 4) between the center of the hinge and the center of the fastening device is greater, and thus the device is not so heavily burdened and accordingly the fastening device can be small.

(2) Since the fastening device does not protrude from the top of the operator's cab, it will not be damaged by obstacles. The tubular support element also functions as a handle outside of the operator's cab, and presents a good appearance.

(3) It is operationally convenient to unfasten the ajar door from inside the operator's cab.

FIG. 1 is a perspective view of an operator's cab provided with a fastening device of the invention;

FIG. 2 is an enlarged perspective view of the fastening device shown in FIG. 1;

FIG. 3 is a perspective view of a striker;

FIG. 4 is a sectional plan view of the fastening device when the door is closed;

FIG. 5 is a sectional plan view of the fastening device when the door is ajar and fastened;

FIG. 6 is a perspective view of the operator's cab provided with the conventional fastening device fixed thereto;

FIG. 7 is an enlarged perspective view of the fastening device shown in FIG. 6;

FIG. 8 is a front view of the conventional fastening device; and

FIG. 9 is a plan view of the device shown in FIG. 8.

An embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an exterior perspective view, and FIG. 2 is an enlarged perspective view of the fastening device indicated as X in FIG. 1.

One end of an outwardly extending door 2 is swingably fixed to a side 3 of an operator's cab 1 by means of a hinge 4. A plate support element 5 and one end of a tubular support element 6 are fixed, and fastened to the outer surface of the door 2 by means of bolts 7 and 8 resepctively, with the other end of tubular support element 6 being secured to the outer end portion of plate support element 5. The inner end of the plate support element 5 is fixed to the outer surface of the door 2 at a point adjacent to the center of the hinge side of the door 2. The tubular support element 6 is three-dimensionally formed so that it will not block the operator's line of vision indicated by the arrow S in FIG. 1. A U-shaped striker 10 shown in FIG. 3 is fastened to an outer end portion the plate support element 5 by means of nuts 11. A lock 20 is fastened by a bolt 26 to the position corresponding to the striker 10 on the side 3 of the operator's cab 1, for holding the striker 10 when the door 2 is in the desired ajar position. A releasing lever 30 of the lock 20 protrudes into the operator's cab 1.

FIG. 4 is a sectional plan view of the lock 20 wherein a bracket 21 is fastened to the side 3 of the operator's cab 1 adjacent to the door 2 by the bolt 26, and a hook 22 having an engaging surface 25 is secured pivotally to the bracket 21 by means of a pin 23. The hook 22 is urged counterclockwise as indicated by the arrow A, by a torsional spring 24. The releasing lever 30, which includes a handle 32 and a lever arm 31 having an engaging surface 33, is pivoted to the bracket 21 by a pin 34. The lever arm 31 is urged clockwise as indicated by the arrow B by a torsional spring 35. The lever 30 protrudes into the operator's cab through the side 3.

A description of the operation will be given. FIG. 4 shows the door 2 closed. When the door 2 swings on the hinge 4 and opens, the striker 10 pushes up the hook 22 and rotates the hook 22 clockwise against the force of the torsional spring 24 so as to allow the engaging surface 25 of the hook 22 and the engaging surface 33 of the lever arm 31 to engage as shown in FIG. 5 and the hook 22 to hold the striker 10, thereby fastening the ajar door 2. The lock is returned to the released condition shown in FIG. 4 by rotating the releasing lever 30 counterclockwise as indicated by the arrow C in FIG. 5 so as to allow the two engaging surfaces to disengage and the hook 22 to swing counterclockwise by the force of the torsional spring 24.

The present invention is useful as a device for fastening an ajar door, which device is small in size, presents a good appearance, and is easy to unfasten, and more particularly, is useful as a device for fastening the ajar door of the operator's cab of a construction machine.