A device for measuring rotational speed includes a housing comprising a base including vertical first and second end walls, and a cover including a window; a lower drive mechanism including a shaft including a gear adjacent to an inner surface of the first end wall, and gear elements rotatable around the shaft in a suspended manner, each gear element including first teeth and second teeth alternated with the first teeth; and an upper counter assembly including a reset shaft including a wing handle and a groove; a gear member rotatable around the reset shaft in a suspended manner and meshed with the gear, the gear member including a projection; and a first number wheel and second number wheels arranged from the gear member to the second end wall sequentially on the reset shaft. Each of the first and second number wheels is a ratchet type device.

A counter containing a first ring member having first indicia and a second ring member having second indicia, each of the first and second ring members being rotatable in increments about a common axis, one or both of the first and second indicia indicating a count; and a drive mechanism for rotating the first ring member and for rotating the second ring member after one or more predetermined degrees of rotation of the first ring member, wherein the drive mechanism contains a pawl-and-teeth mechanism which contains a first and second pawl engageable with a plurality of teeth, and wherein each of the first and second pawls contains a driving engagement face for engaging in a driving engagement with one of the plurality of teeth, and a sliding engagement face for sliding over one of the plurality of teeth.