507 Mechanical Movements

186

Apparatus for disengaging the eccentric-rod from the valve-gear

Apparatus for disengaging the eccentric-rod from the valve-gear. By pulling up the spring handle below until it catches in the notch, a, the pin is disengaged from the gab in the eccentric-rod.

Only the input is driven; every other part of this model moves by physics (MuJoCo), and its ratios are measured. Run it live, change its parameters, or switch the friction off to see the output stop.

Modelled as
An eccentric (the one driven joint, 30 rpm) works the eccentric rod through a 13 cm link; the rod slides 4.8 cm in its guide and its gab (a notch between two jaws, 0.12 cm play) holds the pin of a 7 cm rock-shaft arm. The gab end is hinged with a spring; at 5 s a hand-schedule lifts its spring rest position (the spring handle pulled up and caught in the notch a) so the notch clears the pin. No gravity. gen186.py.
Measured
Engaged: the rock-shaft arm follows the rod at -14.58 rad/m (kinematic asin: -14.58), r2 0.9998, +-20 deg; after the lift the gab stays up (0.25 rad) and the rock-shaft stands (0.007 rad/s) while the rod goes on at 4.8 cm stroke; penetration 0.04 mm.
Notes
Putting the gab back is not modelled (the pin would have to be brought back under the notch); the spring handle and catch a are a hand-set spring rest position rather than a modelled latch.

Film (MP4) · GIF · Still (PNG) · Spec (YAML) · Model (MJCF)

Figure 186 from Brown, 1868
Brown's figure 186 (1868)