Patent GB-190413708-A (GB)
Title: An Improved Speed Indicator
Inventor: BANKS BERTIE
Filed: 1904-06-17
Granted: 1905-05-18
Abstract: 13,708. Banks, B. June 17. Speed indicators.-A spring-driven rack is allowed to rotate a pointer for a time depending on the speed, the pawl of a ratchet wheel being raised during this time by means actuated from a tappet device on a running-wheel. The form shown in Fig. 3 comprises a spindle bearing the pointer and carrying also a ratchet - wheel O, a rackwheel N, and a worm-wheel M. The rack P is spring-pulled and rotates the spindle when the pawl R is lifted, the worm spindle carrying a fan m<1> for timing-purposes. In line with the main spindle is another, carrying loosely a ratchet-wheel, a second ratchet-wheel with one tooth less and having one pair of teeth double the normal distance apart, and a third wheel with one tooth only. These three wheels are connected. Upon the third wheel rests an arm S, fixed to the pawl shaft, the pawl being released when the arm is raised by the tooth of this wheel. The second incomplete ratchet-wheel is moved around one division at each revolution of a cycle or other wheel by a spring-pressed hook B, which is connected by a wire or otherwise to a pivoted lever, mounted on a motor-cycle fork, for example, and adapted to be struck by a projection fixed to a spoke. When the driving-hook engages the tooth of the second incomplete ratchet-wheel next to the double space, the single tooth of the third wheel, by raising and then lowering its arm S, releases the pawl-wheel O for a short time. During this time, the indicating- pointer is rotated by the rack P a distance depending on the speed of the cycle. The stem of a second hook B<1> engaging the first ratchet-wheel ends in a fingerplate b2 through which passes the stem of the first hook, a spring connecting the plate and the end of this stem. Upon the stem of the second hook slides the driving-rack P, its spring being connected to this stem. The fingerplate b<2> is pressed towards the casing when the apparatus is to be used, stretching the rack spring. This also causes the second hook B' to drive the first ratchet-wheel and thus to turn the second incomplete ratchet-wheel until it can be driven by the first hook B. The fingerplate spring also draws in the first hook and, by tightening the connection to the pivoted lever mounted on the cycle fork, brings this lever into position to be struck. When the fingerplate is released, the rack returns the indicating-pointer to its initial position. In a modification, Fig. 5, the first hook B is pivoted, the pivot carryiug a rod b<5> to which the connecting- wire C is attached. The pawl-wheel O is carried by the worm - spindle, the single-toothed wheel is replaced by a projection on the complete ratchetwheel, and the arm projects from the pawl R. The second hook stem is pressed outwards, and an extension from it bears against the rod b<5> attached to the first hook. This rod has pivoted to it another rod, passing through the extension of the second hook stem, to which it is connected by a spring. A pawl X is provided to prevent backward rotation of the complete and incomplete ratchetwheels ; and in this form the dial rotates and the pointer is fixed. The rack spring 1) is also carried by an arm of the second hook stem, and is compressed instead of extended when in action. The device is stated to be applicable to engines, and to motors or other road vehicles. The Provisional Specification also mentions that clockwork mechanism may be used.