HAND CONTROL VALVE

Abstract: A locking mechanism for a hand control valve in which in­ stead of a single sleeve movable along the lever to engage and disengage an enlarged opening in a guide slot for the lever, two movable sleeves are provided. One sleeve, usually the low­ er sleeve, which enters the opening or engages any other abutment is biased upwardly away from the locking position. The upper sleeve is biased in the opposite direction so tending to urge the lower sleeve into the locking position. When the upper sleeve is lifted the lower sleeve remains in the locked position, being held by friction acting between the sleeve and the edge of the locking opening. Only when the lever is pulled back against its torsion loading spring is the lower sleeve ejected to release the lever. The locking mechanism is then more secure than conventional mechanisms.

Description: HAND CONTROL VALVE This invention relates to a lever locking mechanism particularly but not exclusively for a hand control valve such as used for vehicle braking systems. Such hand control valves normally have an operating lever which is automatically locked into a "park" position by means of a movable locking member which is biased toward a locked position wherein it engages an abutment disposed in a position corresponding to the park position of the lever. Usually, the locking member is in the form of a sleeve disposed around and slidable along the lever and is biased by an internal spring so as to enter an enlarged circular opening at the end of the lever guide slot corresponding to the park position. To release the lever, whereupon it is returned to the "brakes-off" position by a torsion spring, the sleeve must be withdrawn from the circular opening in opposition to the action of the internal spring. This arrangement is not sufficiently secure to comply with the safety regulations in force in certain countries. iMat we propose in accordance with the present invention is a lever locking mechanism comprising two movable members, preferably sleeves slidable along the lever, and one of which, in a locking position thereof, prevents movement of the lever by, for example, engaging behind an abutment, and is biased away from the locking position toward a release position, the other member being biased into abutment with the said one member so tending to urge it into the locking position. In a preferred embodiment a lower sleeve, which in the locked position enters an enlarged opening in a guide slot for the lever to prevent movement of the lever, is biased upwardly away forn the locked position and on upper sleeve is biased downwardly tending to hold the lower sleeve in the locked position. With such a mechanism in a otherwise conventional hand control valve of the kind described above, locking in maintained, but when the upper sleeve is pulled up, the lower sleeve remains in the locked position, being held by friction acting between the sleeve and the edge of the circular opening. Only when the lever is pulled back against the torsion spring, is the lower sleeve ejected from the opening to release the lever. One advantage of a locking mechanism according to the present invention is that the lower locking sleeve is subject only to a light locking spring load. The extensive wear associated with the conventional locking mechanism, is avoided. The invention also includes a hand control valve the operating lever of which is fitted with a lever locking mechanism according to the invention. An embodiment of the invention will now be described with reference to the accompanying drawings at which: Figure 1 is a cross-sectional view of a hand control valve having a lever fitted with a locking mechanism to the present invention; and Figure 2 is a part cross-sectional and elevation of the hand control valve shown in Figure 1. The lever 10 is movable in an arc, to control the valve 11, through a guide slot 12 having at one end, corresponding to a "park" position an enlarged circular opening (not shown) of a diameter sufficient to receive a lower sleeve 3 around the lever 10. This sleeve 3 is biased radially outwardly along the lever (i.e. away from the position shown) by a light spring 5 within the sleeve 3. Radially outwardly along the lever 10 is a second sleeve 2 which is biased radially inwardly along the lever (i.e. toward the locked position shown) by a spring 1 disposed between the sleeve 2 and the lever and abutting a shoulder 14 on the lever. The spring 1 is more powerful than the spring 5. In operation, when the lever 10 is moved to the "park" position both sleeves move together under the action of the spring 1 in opposition to spring 5 such that the lower sleeve 3 enters the enlarged circular opening and thus locks the lever in the "park" position. Should the operator simply raise the upper sleeve 2 against the spring 1 the lever will not be released since the friction acting between the lower sleeve 3 and the sides of the enlarged opening due to the action of a torsion spring 4 tending to return the lever to the brakes-off position, is not overcome by the spring 5. To release the lever, the operator must, in addition to raising the upper sleeve 2, also pull back the lever 10 from its locked position, to relieve the pressure applied by the torsion spring 4. This done, the lower sleeve moves outwardly along the lever under the action of the spring 5 so allowing the lever to traverse the guide slot to the "brakes-off" position.

Claims: CLAIMS 1. A lever locking mechanism comprising two movable members associated with the lever and one of which, in a locking position thereof, prevents movement of the lever and is biased away from the locking position, the other member being biased into abutment with the said one member so tending to urge it into the locking position. 2. A mechanism according to claim 1 wherein in the locking position, the said one member engages behind an abutment so preventing movement of the lever. 3. A mechanism according to claim 2 wherein the lever is biased so as to urge the said one member against the abutment in the locking position. 4. A lever locking mechanism according to any one of claims 1 to 3 wherein at least the said one movable member is a sleeve around the lever, the lever being movable along a guide formed with a recess for receiving the sleeve in the locking position so preventing movement of the lever. 5. A lever locking mechanism according to claim 4 wherein the other movable members is also a sleeve around the lever. 6. A mechanism according to any one of the preceding claims wherein the said one member is a lower sleeve biased upwardly away from the locking position and the other member is an upper sleeve biased downwardly against the lower sleeve both sleeves being slidable along the lever and wherein in the locked position the lower sleeve is received by an enlarged opening in a guide slot for the lever. 7. A mechanism according to claim 6 wherein the upper sleeve is adapted and arranged to be raised by hand against the bias when operating the lever. 8. A lever locking mechanism constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings. 9. A hand control valve for a vehicle braking system operable by a lever and including a lever locking mechanism according the any one of the preceding claims, the lever being biased away from a "park" position wherein the lower sleeve takes up the locking position, toward a "brakes-off" position.

Inventors: COUPLAND, RALPH
Applicants: CLAYTON DEWANDRE COMPANY LIMITED
Application year: 1982
Main classification: G05G5
IPC codes: B60T15, G05G5