A rail vehicle unit, comprising - a running gear and a wagon body unit (101.1) forming two contact partners and defining a longitudinal direction, a transverse direction and a height direction; - said wagon body unit (101.1) being supported on said running gear via a suspension device; - a first rotational buffer device and a second rotational buffer device being associated to said running gear and said wagon body unit (101.1); - said first rotational buffer device and said second rotational buffer device being adapted to damp a rotational motion between said running gear and said wagon body unit (101.1) about a rotational axis parallel to said height direction; characterized in that - said first rotational buffer device and said second rotational buffer device are configured to form a traction link between said running gear and said wagon body unit (101.1); - said traction link being configured to transmit at least a major fraction of a total traction force to be transmitted along said longitudinal direction between said running gear and said wagon body unit (101.1), wherein - at least one of said first rotational buffer device and said second rotational buffer device is connected to a first contact partner of said two contact partners (102, 101.1); - at least one of said first rotational buffer device and said second rotational buffer device having a first contact surface (119.4); - a second contact surface (101.2) being formed at a second contact partner (101.1) of said two contact partners (102,101.1); - said first contact surface (119.4) and said second contact surface (101.2) being configured to contact each other to transmit said fraction of said total traction force between said running gear and said wagon body unit (101.1); - said first contact surface (119.4) and said second contact surface (101.2), in a neutral state of said rail vehicle unit, being separated by a longitudinal gap having a longitudinal gap dimension in said longitudinal direction. - a running gear and a wagon body unit (101.1) forming two contact partners and defining a longitudinal direction, a transverse direction and a height direction; - said wagon body unit (101.1) being supported on said running gear via a suspension device; - a first rotational buffer device and a second rotational buffer device being associated to said running gear and said wagon body unit (101.1); - said first rotational buffer device and said second rotational buffer device being adapted to damp a rotational motion between said running gear and said wagon body unit (101.1) about a rotational axis parallel to said height direction; - said first rotational buffer device and said second rotational buffer device are configured to form a traction link between said running gear and said wagon body unit (101.1); - said traction link being configured to transmit at least a major fraction of a total traction force to be transmitted along said longitudinal direction between said running gear and said wagon body unit (101.1), wherein - at least one of said first rotational buffer device and said second rotational buffer device is connected to a first contact partner of said two contact partners (102, 101.1); - at least one of said first rotational buffer device and said second rotational buffer device having a first contact surface (119.4); - a second contact surface (101.2) being formed at a second contact partner (101.1) of said two contact partners (102,101.1); - said first contact surface (119.4) and said second contact surface (101.2) being configured to contact each other to transmit said fraction of said total traction force between said running gear and said wagon body unit (101.1); - said first contact surface (119.4) and said second contact surface (101.2), in a neutral state of said rail vehicle unit, being separated by a longitudinal gap having a longitudinal gap dimension in said longitudinal direction.