dynamometer

n. [ Cf. F. dynamomètre. See Dynameter. ] An apparatus for measuring force or power; especially, muscular effort of men or animals, or the power developed by a motor, or that required to operate machinery. [ 1913 Webster ]

☞ It usually embodies a spring to be compressed or weight to be sustained by the force applied, combined with an index, or automatic recorder, to show the work performed.