Convex wheel chock and chock extractor
A wheel chock includes a convex load surface configured to be engaged by a vehicle tire. The resultant force exerted by the vehicle tire on the wheel chock can be expressed as a vector normal to the convex surface, at a contact angle θ. As dynamic loading forces push the vehicle into the wheel chock, the tire rides up the convex surface of the chock, thereby increasing the contact angle θ. For contact angles greater than 45°, the vertical component of the resultant force will increase, and the horizontal component will decrease. The net effect is that, under dynamic loading, the chock will tend to anchor itself downwards rather than slide backwards or tip over. Also disclosed is a chock extractor secured to the wheel chock. Rotating the extractor handle in turn rotates an extractor foot, which pivots and lifts the wheel chock off the ground to disengage the chock.
1. A convex wheel chock restraining system for a vehicle tire, comprising:
a wheel chock, the wheel chock comprising:
a contact surface configured to face generally towards the tire to be engaged by the wheel chock;
a support element connected to the contact surface and configured to transfer a tire load from the contact surface;
a base portion coupled to the support element, configured to provide structural support to the wheel chock and transfer the tire load to a ground surface;
wherein the contact surface comprises a convex surface extending generally upwards from the base portion to the support element, the convex surface configured to be engaged by the tire;
at least one projection extending from the base portion, configured to concentrate the load path to the ground surface;
and;
a wheel chock extractor, the wheel chock extractor comprising:
a mounting bracket secured to the wheel chock;
an extractor sleeve coupled to the mounting bracket;
a shaft rotatingly disposed within the extractor sleeve;
wherein the extractor sleeve is configured to provide a bearing surface and guide for the shaft;
an extractor foot coupled to the shaft and configured to engage the ground surface; and
an actuator coupled to the shaft and configured to provide mechanical advantage to rotate the shaft;
wherein the extractor foot and the actuator are configured to rotate with the shaft.
2. The convex wheel chock restraining system according to claim 1 , wherein the contact surface further comprises a concave extension surface joined to an upper end of the convex surface.
3. The convex wheel chock according to claim 2 , wherein the upper end of the convex surface is positioned at an angle in a range between 20 and 30 degrees relative to the base portion.
4. The convex wheel chock according to claim 1 , wherein the wheel chock further comprises an aperture in the convex surface of the contact surface, and a sensor configured to detect the presence of the tire through the aperture, wherein the sensor is configured to provide input for a dock safety sensor system.
5. The convex wheel chock according to claim 4 , wherein the dock safety sensor system comprises an indoor-mounted control panel in proximity to a loading dock overhead door, and the sensor, upon sensing the presence of the tire, is configured to send an indication to the control panel, whereupon the control panel is configured to indicate safe operation of the overhead door.
6. A chock extractor for removing a wheel chock, comprising:
a mounting bracket;
an extractor sleeve coupled to the mounting bracket;
a shaft rotatingly disposed within the extractor sleeve;
an extractor foot coupled to the shaft and configured to engage a ground surface; and
an actuator coupled to the shaft and configured to provide mechanical advantage to rotate the shaft.
7. The chock extractor of claim 6 , further comprising a hand hold mechanically coupled to the actuator.
8. The chock extractor of claim 6 , further comprising a cam element coupled to an internal surface of the wheel chock, the cam element configured to position the actuator at rest in a predominantly upright position.
9. The chock extractor of claim 6 , wherein the mounting bracket comprises a bend to form an acute angle, the bend having a radius sufficient to form an internal pocket, and wherein the extractor sleeve is secured to the mounting bracket at the bend pocket.
10. The chock extractor of claim 6 , wherein the actuator comprises a power-actuated rotational actuator.