(1) Ensure that the trailer has a good ride.
(2) Have the appropriate ability to attenuate vibration.
(3) When the trailer is braking or accelerating, it is necessary to ensure the stability of the vehicle body, reduce the vehicle body pitch, and the vehicle body roll angle when turning is appropriate.
(4) Compact structure and small space size.
(5) Reliably transmit various forces and moments between the vehicle body and the wheels, while ensuring that the quality of parts is small, sufficient strength and life must be ensured.