A baffle plate is arranged between a crankshaft axially supported in a freely rotating manner by a cylinder block and a bearing cap and an oil pan storing lubricating oil supplied to each part of a vehicle engine. When the bridge itself is not settled in a root bridge, a transmitter transmits to another bridge a TCN-BPDU that, when the bridge itself has received a BPDU inferior to itself BPDU, the representative bridge changes. The adjuster includes an adjuster input shaft, which is actuated by a brake operating shaft, and an adjuster body that supports first and second adjuster members. Each of the P2P tags selects a timeslot at random from the period for each type, and after waiting for a waiting period at random at the selected timeslot, it transmits a frame including information to identify the selected timeslot or the waiting period in addition to its own ID. Thanks to the above steps, the present method allows to operate with a reduced amount of catalyst in the catalytic bed, keeping however the fluid dynamics and pressure drop characteristics unchanged.