Question: We have a baby swing that is operated by winding it up. Can we use it on Shabbos?
Answer: The Shulchan Aruch (OC 338:3) writes that one can set an old clock before Shabbos even though it will chime throughout Shabbos. The Mishna Berura (338:14) explains that people will understand that it was set before Shabbos. The poskim discuss whether one can pull the chains that operate the clock on Shabbos. The Mishna Berura (338:15) paskens like the Chayei Adam (44:19) who writes that it is forbidden because it is akin to tikkun mana (fixing something). The Chazon Ish (OC 50:9) also says it is forbidden, though explains that as you are making the watch operational again, it is akin to boneh (building).
As there is a machlokes as to whether one can wind a watch on Shabbos that is still ticking (See Ksav Sofer OC 55; Daas Torah OC 338:3), the Mishna Berura (338:15) and R’ Yehoshua Neuwirth (Shemiras Shabbas Kehilchasa 28:20) pasken, that one may only do so under extenuating circumstances, such as for a choleh.
The poskim discuss whether wind-up toys and swings are included. R’ Yisroel Pinchos Bodner (Tiltulei Shabbos 1:n36) writes that he heard from R’ Moshe Feinstein that one mustn’t play with wind-up toys on Shabbos as they are like winding up watches.
R’ Yehoshua Neuwirth (ibid. 16:14) writes that children can play with wind-up toys providing they don’t make a noise, etc. He writes that R’ Shlomo Zalman Auerbach differentiated between watches and toys. Watches are considered to be non-operational when not ticking, as opposed to wind-up toys that are only designed to work for a few seconds. Additionally, watches are far more complex and sophisticated than wind-up toys (See Minchas Shlomo 9; Be’er Moshe 6:32). He writes that they may be assur miderabanan according to the Chazon Ish, however.Thus, R’ Ribiat (The 39 Melochos, p1132) writes that one may wind up a baby swing on Shabbos. He writes (ibid. Makeh Bepatish n58) that while R’ Moshe’s prohibition of wind-up toys may apply to wind-up swings, too, he heard from many poskim that one may wind up baby swings on Shabbos.