Rollover protection apparatus

1. A rollover protection apparatus, comprising:

(a) roll bar assembly including a lower portion that is mounted to a vehicle frame and an upper portion which is pivotably mounted to the lower portion so that the upper portion is operable to pivot between a raised position and a lowered position, the upper portion being biased toward the raised position,

(b) a releasable lock associated with the upper portion and the lower portion for securing the upper portion in the raised position, and,

(c) a lock releasing device for releasing the releasable lock associated with the upper portion and the lower portion, such that when the lock releasing device is activated, the releasable lock releases so that an overhead obstacle is able to move the upper portion of the roll bar assembly toward the lowered position as the roll bar assembly passes under the overhead obstacle and whereby the upper portion, being biased toward the raised position, returns to the raised position after clearing the overhead obstacle, and, so that if the lock releasing device is no longer being activated, the lock returns to the locked position thereby securing the upper portion in the raised position.

2. The rollover protection apparatus of claim 1 , wherein:

the releasable lock is arranged such that the releasable lock is not able to return to the locked position unless the upper portion of the roll bar assembly is in the raised position.

3. A rollover protection apparatus, comprising:

(a) roll bar assembly including a lower portion that is mounted to a vehicle frame and an upper portion that is pivotably mounted to the lower portion, the upper portion operable for pivoting between a raised position and a lowered position, the upper portion being biased toward the raised position,

(b) a releasable lock associated with the upper portion and the lower portion for securing the upper portion in the raised position,

(c) a lock releasing and upper portion actuation device that is operable for releasing the releasable lock and for pivoting the upper portion of the roll bar assembly from the raised position toward the lowered position,

(d) a manual actuator operatively associated with the lock releasing and upper portion actuation device, the manual actuator arranged such that when the manual actuator is moved from a first position to a second position the releasable lock is unlocked and such that when the manual actuator is moved from the second position toward a third position, the upper portion of the roll bar pivots away from the raised position toward the lowered position.

4. The rollover protection apparatus of claim 3 , wherein:

the manual actuator is selected from a group consisting of a pedal and a lever.

5. The rollover protection apparatus of claim 3 , wherein:

the upper portion of the roll bar assembly is biased to return the raised position when the manual actuator is in the first position or the second position.

6. The rollover protection apparatus of claim 5 , wherein:

the lock is biased to return to the locked position and the upper portion and the lower portion of the roll bar are arranged such that the lock will return to the locked position if the upper portion of the roll bar is in the raised position and the manual actuator is in the first position.

7. The rollover protection apparatus of claim 6 , wherein:

the manual actuator and the lock releasing and upper portion actuation device are arranged such that if the manual actuator is moved from the second position toward the third position and if subsequent to such movement of the manual actuator, the application of manual force to the manual actuator ceases, the manual actuator will return to the first position, the upper portion will return to the raised position and the releasable lock will re-engage to lock the upper portion in the raised position.

8. A rollover protection apparatus, comprising:

(a) roll bar assembly including a lower portion that is mounted to a vehicle frame and an upper portion which is pivotably mounted to the lower portion for pivoting between a raised position and a lowered position,

(b) a releasable lock associated with the upper portion and the lower portion for securing the upper portion in the raised position,

(c) a lock releasing and upper portion actuation device that is operable for releasing the releasable lock and for moving the upper portion from the raised position toward the lowered position, and,

(d) a movable element suitable for receiving a manually applied force, the movable element operably associated with the lock releasing and upper portion actuation device such that when a force is applied to the movable element, the releasable lock unlocks and the upper portion pivots toward the lowered position and such that if the application of the force to the movable element ceases, the upper portion pivots back to the raised position and the releasable lock re-engages to secure the upper portion in the raised position.