??????? ???? ???? ??? ??????? ?????? ???? ????? ????? ?? ??? ??? ???? ??????? ?????? ??????? ??????? ???????? ???? ????? ???????? ???? ????? ?????? ??????? ?? ?? ????? ?? ???????? ??? ???? ?? ??????? ???? ?????? ????? ?? ??????? ????? ?????? ????? ??????? ??????? ?????? ????? ??????? ??????. devoid of gears, the push resists shocks and vibrations