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car parking lock

car parking lock

car parking lock


I have to understand how a parking lock described in a patent works, but I cannot really get it.
The text is french, however, there is an online translation into English.

The link to the patent is the following: [URL="http://worldwide.espacenet.com/publicationDetails/..."]http://worldwide.espacenet.com/publicationDetails/...[/URL]

On the left hand you can see the tab: Description. If u click on it, you get the french text. Above the text there is a button for the translation.

The Figures are to be found in the tab "Mosaics".

My main question is in which state the spring 22 is Fig.1 and 2. Spring 22 is shown to be compressed in Fig. 1, but I cannot really understand how the thing works in terms of the motion and the spring.

As a general description, as cam 7 is turned, element 14 goes to the left, so that carriage 20 causes the latch 8, more specifically part 27 of the latch to tun and get into the gear 27, so as to achieve a locked position. But I have problems understanding how the spring 22 reacts. Spring 10 should from what I understood be in a "compressed" state in Fig. 2, so as to exert a force in the direction of arrow 11, trying to get the latch 8 out of the gear 2.

Could you please help me get a bit further?


RE: car parking lock


Referring to fig.1, the actual locking device is the pawl (27) that engages a slot in the wheel (2). When disengaged, the follower assy (20) is positioned at the rightward limit of its travel, and the pawl lever (8) is rotated CCW by a spring (10) disengaging the pawl from the wheel slot to allow the load shaft (1) to turn freely.

To engage the brake, the cam (7) rotates approx. 45deg CCW and the scotch yoke follower (14) translates to the left. The scotch yoke follower is guided by pins (16) in slots (17). The pawl lever is rotated CW and locked in place by a roller (24) attached to the follower assy (20) bearing against a ramp surface (30) on the pawl lever. The follower assy movement is constrained in the vertical direction by a roller (25) attached to the follower bearing against a fixed horizontal surface (26). Force is transferred from the scotch yoke frame to the follower thru a sliding guide rod (21) and compression spring (22). The sliding guide rod and compression spring function to provide a controlled amount of force applied to the follower assy by the scotch yoke actuator.

Hope that helps.

RE: car parking lock

Thanks, Terry, for the reply!

I agree on that, however, I cant understand how the sping in Fig. 2 seems to be in its natural state or extended in comparison with thhat in Fig. 1 when the yoke 14 moves to the left. Should it not compress the spirng more?

Could you please give me an answer with regard to what state the sping is in Fig. 1 and Fig. 2?

Thanks again.

RE: car parking lock


I hope I did not mislead you. I am not fluent in French, so I was not able to understand the patent text. The functional description I provided was based just on what I could discern from the patent drawings of the mechanism.

I would agree that the relative change in length of the compression spring (22) as shown in figs 1&2 is a bit confusing. One function of the spring is to allow the scotch yoke frame to translate left when the follower assy is blocked from translating left by the pawl lever being unable to rotate CW, due to the tip of the pawl not being aligned with a slot in the wheel. In this condition (fig.1) where the pawl tip is riding on the wheel OD between slots, the spring would be compressed from translation of the scotch yoke actuator. As soon as the wheel rotates sufficiently in either direction, the pawl will drop into a slot, the follower assy will be free to translate leftward a small distance, and the spring will expand a bit in length as shown in fig.2.

Hope that helps.

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