Speed change control device for a continuously variable transmission

A speed change control device for a continuously variable transmission comprising:

• a trunnion which supports power rollers gripped between input/output disks free to rotate, and is able to rotate around an axis and displace in an axial direction,
• a hydraulic cylinder which drives the trunnion in the axial direction, and
• a speed change control valve which controls an oil pressure supplied to this hydraulic cylinder, wherein
• the speed change control valve comprising;
• a spool which is free to displace and is housed in the speed change control valve and provides a first land which can face a supply port supplying a supply pressure and second lands which can respectively face first and second drain ports formed on either side of the supply port,
• first output port is provided for allowing a first oil chamber provided in the hydraulic cylinder to selectively communicate with the supply port or the first drain port according to the displacement of the spool,
• second output port is provided for allowing a second oil chamber provided in the hydraulic cylinder to selectively communicate with the supply port or the second drain port according to the displacement of the spool,
• the first land faces the supply port and the second lands face the first and second drain ports in a neutral position of the spool, and
• the width of the first land is set to be equal to or greater than the width of the supply port, and the width of the second lands are set to a width at which the first drain port communicates with the first output port which is formed between the first drain port and the supply port and the second drain port communicates with the second output port which is formed between the second drain port and the supply port in the neutral position of the spools.