Abstract: The present invention provides a valve seat of a Co-free, sintered iron-based alloy having excellent heat resistance, oxidation resistance and wear resistance, as well as excellent machinability, which is usable for internal combustion engines using a gas fuel. The valve seat is produced by using a prealloy containing 12% or more by mass of Cr in a matrix for, and hard particles having high strength and hardness at high temperatures are used, such that the entire valve seat has a composition comprising by mass 5.0-20.0% of Cr, 0.4-2.0% of Si, 2.0-6.0% of Ni, 5.0-25.0% of Mo, 0.1-5.0% of W, 0.5-5.0% of V, 1.0% or less of Nb, and 0.5-1.5% of C, the balance being Fe and inevitable impurities.

Abstract: The present invention provides a valve seat of a Co-free, sintered iron-based alloy having excellent heat resistance, oxidation resistance and wear resistance, as well as excellent machinability, which is usable for internal combustion engines using a gas fuel. The valve seat is produced by using a prealloy containing 12% or more by mass of Cr in a matrix for, and hard particles having high strength and hardness at high temperatures are used, such that the entire valve seat has a composition comprising by mass 5.0-20.0% of Cr, 0.4-2.0% of Si, 2.0-6.0% of Ni, 5.0-25.0% of Mo, 0.1-5.0% of W, 0.5-5.0% of V, 1.0% or less of Nb, and 0.5-1.5% of C, the balance being Fe and inevitable impurities.

Abstract: A multi-commander includes a first memory for storing a plurality of remote control signals having different signal formats, a circuit for receiving a remote control signal from another remote commander, a rewritable second memory, a remote control signal transmitting circuit for transmitting a remote control signal derived from the first memory, and a mode switch for selectively switching between the setting mode and the remote control mode. When the mode switch is in the setting mode, the signal format of the remote control signal derived from the other remote commander and received by the remote control signal receiving circuit is identified and the signal format of the remote control signal from the other remote commander is read out of the first memory and is then written in the second memory.