Patent ID: 7658128

Claim:
A transmission housing for a four wheel drive system, comprising: a transmission housing member to enclose a transmission mechanism; a transfer housing member to enclose a transfer to apportion a driving torque from the transmission mechanism between front wheel's side and rear wheel's side; and a converter housing member to enclose a torque converter to be connected between an engine and the transmission mechanism, the converter housing member including: an engine mount portion on a first side of the converter housing member, the engine mount portion being formed integrally in the converter housing member; a transfer mount portion defining a first side joint surface on the first side, the transfer mount portion being formed integrally in the converter housing member, the transfer housing member being joined to the first side joint surface of the transfer mount portion; a transmission housing mount portion including a flange and defining a second side joint surface on a second side of the converter housing member opposite to the first side, the transmission housing mount portion being formed integrally in the converter housing member, the transmission housing member being joined to the flange of the transmission housing mount portion; and first and second reinforcing ribs formed between the first side joint surface and the second side joint surface; wherein the first reinforcing rib extends in a vertically extending first direction, from a rib connecting portion formed at a position contacting with an inner circumference of the flange of the transmission housing mount portion; the second reinforcing rib extends in a horizontally extending second direction from the rib connecting portion; and the first and second reinforcing ribs are provided so as to surround a drive shaft to transmit driving power from the transmission mechanism to the transfer.