Transmission clutches with sequence valve and piston-controlled pressure modulator

In transmission hydraulic controls mechanism wherein speed and direction clutch systems are provided, both disposed to receive modulated actuating hydraulic fluid, a valve assembly comprising:

• a reducing valve disposed to receive actuating main rail hydraulic fluid, said reducing valve having a fluid output wherein the pressure of the fluid at the output is reduced at a range below main rail pressure;
• a control piston associated with the reducing valve for increasing the actuating pressure of the fluid at the reducing valve output, with said increase at constant rate;
• a valve body in the assembly common to the valve and piston and coaxially slidably receiving same;
• said assembly provided with an internal bypass around the piston characterized by a bypass land (170) and means (172) affording therepast bypass-blocked and direct bypass-open conditions, and having its opposite ends intersecting the bore at two points disposed hydraulically adjacent the respective opposite ends of the piston;
• first means connected hydraulically to said bore effective during the bypass-blocked condition to introduce restricted flow of output fluid between the valve and piston to hydraulically cause relative separative movement therebetween from a reset position of the piston adjacent the valve;
• second means effective during the bypass-blocked condition for introducing resistance to relative separative movement by the piston, controlling speed of the latter and building up valve back pressure between the valve and piston;
• and
• third means connected to the piston effective during the direct bypass-open condition so as to cause the piston to quickly reset to reset position by direct replenishment of the volume evacuated therebehind, with that fluid being immediately displaced ahead of the piston.

In transmission hydraulic controls mechanism wherein speed and direction clutch systems are provided, both disposed to receive modulated actuating hydraulic fluid, a valve assembly comprising:

• a reducing valve disposed to receive actuating main rail hydraulic fluid, said reducing valve having a fluid output wherein the pressure of the fluid at the output is reduced at a range below main rail pressure;
• a control piston associated with the reducing valve for increasing the actuating pressure of the fluid at the reducing valve output, with said increase at constant rate;
• a valve bore in the assembly common to the valve and piston and coaxially slidably receiving same;
• said assembly provided with an internal bypass around the piston characterized by a bypass land and means affording therepast bypass-blocked and direct bypass-open conditions, and having its opposite ends intersecting the bore at two points disposed hydraulically adjacent the respective opposite ends of the piston;
• first means connected hydraulically to said bore effective during the bypass-blocked condition to introduce restricted flow of output fluid between the valve and piston to hydraulically cause relative separative movement therebetween from a reset position of the piston adjacent the valve;
• said coaxially slidably related valve and piston defining an intervening valve back pressure chamber in said common bore;
• said first means comprising a restriction (154) in the reducing valve intercommunicating the output and said valve back pressure chamber for causing the relative separative movement hydraulically as described;
• second means effective during the bypass-blocked condition for introducing resistance to relative separative movement by the piston, controlling speed of the latter and building up valve back pressure between the valve and piston;
• and
• third means connected to the piston effective during the direct bypass-open condition so as to cause the piston to quickly reset to reset position by direct replenishment of the volume evacuated therebehind, with that fluid being immediately displaced ahead of the piston.

In transmission hyraulic controls mechanism wherein speed and direction clutch systems are provided, both disposed to receive modulated actuating hydraulic fluid, a valve assembly comprising:

• a reducing valve disposed to receive actuating main rail hydraulic fluid, said reducing valve having a fluid output wherein the pressure of the fluid at the output is reduced at a range below main rail pressure;
• a control piston associated with the reducing valve for increasing the actuating pressure of the fluid at the reducing valve output, with said increase at constant rate;
• a valve bore in the assembly common to the valve and piston and coaxially slidably receiving same:
• said assembly provided with an internal bypass around the piston including a bypass land and means affording therepast bypass-blocked and direct bypass-open conditions, and having its opposite ends intersecting the bore at two points disposed hydraulically adjacent the respective opposite ends of the piston;
• first means connected hydraulically to said bore effective during the bypass-blocked condition to introduce restricted flow of output fluid between the valve and piston to hydraulically cause relative separative movement therebetween from a reset position of the piston adjacent the valve;
• second means effective during the bypass-blocked condition for introducing resistance to relative separative movement by the piston, controlling speed of the latter and building up valve back pressure between the valve and piston, and comprising a drain port intersecting said bore intermediate said two points so as to lie along the path of sliding of the piston;
• said piston having spill orifices (166) of graduated size along the side thereof, having decreasing size as they encounter the drain port during said relative separative movement of the piston from reset position;
• and
• passage means (84) to introduce a body of fluid incoming into said bore ahead of the piston and not trapped because of its restrictive escape afforded by the piston itself through its spill orifices aforesaid.