Speed change control apparatus for continuously variable transmission

A speed change control apparatus for continuously variable transmissions, having a primary pulley to be mounted on a primary shaft and having a pulley groove with a variable width, a secondary pulley to be mounted on a secondary shaft and having a pulley groove with a variable width, a belt wound on both of said primary pulley and said secondary pulley, a primary cylinder mounted on the primary pulley and provided with a primary hydraulic chamber, and a secondary cylinder mounted on the secondary pulley and provided with a secondary hydraulic chamber, said speed change control apparatus comprising:

• a line pressure adjusting valve for adjusting hydraulic fluid supplied from a oil pump into a line pressure;
• a primary pressure adjusting valve for adjusting the line pressure into a primary pressure;
• and
• oil passage switching mechanism for switching an oil passage between a first condition and a second condition, wherein in the first condition, the line pressure is supplied to the secondary hydraulic chamber and the primary pressure is supplied to the primary hydraulic chamber, and wherein in the second condition, the line pressure is supplied to the primary hydraulic chamber and the primary pressure to the secondary hydraulic chamber.