| 摘要 |
An auxiliary brake apparatus is provided that includes an exhaust brake system for restricting a channel area of an exhaust passage so as to increase a resistance to rotary motion of an engine, and a retarder disposed between an automatic transmission and vehicle wheels, for generating a braking force that resists an engine brake torque transmitted to the automatic transmission. The auxiliary brake apparatus further includes a required braking force determining device for determining a braking force applied to a vehicle body during down-shifting, depending upon a vehicle speed and a type of shifting, before the automatic transmission is shifted down while the exhaust brake system is actuated, and a retarder braking force control device for causing the retarder to generate a braking force during the down-shifting so that an engagement load applied to an engaging element of the automatic transmission becomes not greater than a predetermined level when the exhaust brake system and the retarder generate the braking force determined by the required braking force determining device. |
