Abstract: A reciprocating mower unit (14) comprises a reduction gear (54) and a crank mechanism (56) arranged within a housing (24). The reduction gear (54) receives input rotary motion from a transmission shaft at a first, relatively higher, rotation speed, and deliver an output rotary motion to a gear output shaft (58) at a second, relatively lower, rotation speed, whereas the crank mechanism (56) converts the output rotary motion of the gear output shaft (58) to an oscillating, anti-phase motion of a pair of mowing blades (32a, 32b) about a common oscillation axis (A1). The reciprocating mower unit (14) comprises an input shaft (48) provided with a coupling interface (49) for releasably coupling the input shaft (48) to the transmission shaft.