Device for manoeuvring a tension wheel in a chassis of a tracked vehicle, in which the tension wheel is rotatably mounted on a telescopic rocker arm (12). The rocker arm can, on the one hand, be lengthened and shortened by a first hydraulic cylinder and, on the other hand, swivelled about a transverse axis (14) by a second hydraulic cylinder for the purpose of raising and lowering the tension wheel. The first hydraulic cylinder is designed to act upon a lever arm (58) of a sleeve (54) rotatable in a hub part (20) of an inner part (18) of the rocker arm (12), which sleeve has an eccentrically mounted crank pin (52) which is hinge-connected to an outer part (22) of the rocker arm for the purpose of displacing the latter relative to the inner arm part, in the event of a mutual rotation motion between the sleeve (54) and the hub part (20) of the inner rocker arm part, in such a way that the rocker arm is lengthened upon a downward swivel motion of the arm and the tension wheel.