What is a transmission shift valve?
A transmission valve body is a major component of an automatic transmission. It’s essentially a maze-like control center made up of valves, passageways, and solenoids that diverts transmission fluid to where it’s needed for gear changes.
How does a shift valve work?
A rod or cable links the carburetor or fuel injection throttle body to a lever on the transmission. When the operator depresses the throttle, the lever moves the kickdown valve. This action causes hydraulic pressure to over- ride normal shift control pressure and the transmission downshifts.
What types of valves are used in an automatic transmission?
In the December 2016 issue of GEARS Magazine, we learned about the three different types of valves used in all automatic transmissions: regulator valves, switch valves, and servo valves. We also discussed switch valves that can be pulsed on and off by the computer to regulate pressure.
What is the function of the bands in an automatic transmission?
Transmission bands are steel bands that wrap around sections of the gear train and connect to the housing. As the band tightens around the drum, transmission fluid is squeezed out into grooves cut into the band’s surface. The band brings the drum to a stop and holds it there.
What are the 5 basic valves in an automatic transmission?
Types of Valves
- Shift Valves. The vast majority of valves inside of a valve body will be shift valves.
- Shuttle Valve. The shuttle valve exists to allow fluid to flow through it.
- Manual Valve.
- Pressure Reg Valve.
- Kickdown Valve.
- Throttle Valve.
- Governor Valve.
- Vacuum Modulator Valve.
Where is the manual valve in an automatic transmission?
It will be understood that in describing hydraulic fluid circuits, ATF usually changes names when it passes through an orifice or control valve in a specific circuit. The Manual Valve in an automatic transmission is a spool valve connected by linkage or cable to the shift lever inside the passenger compartment.
How does the oil change on an automatic transmission?
The Governor and the Modulator or Throttle Cable that monitor speed and throttle position in order to determine when to shift. On newer vehicles, shift points are controlled by Computer which directs electrical solenoids to shift oil flow to the appropriate component at the right instant.
What kind of valves are in an automatic engine?
The vast majority of valves inside of a valve body will be shift valves. These are simple balance-type spool valves that operate the bands, servos, and gearsets of your engine. Essentially, shift valves are the reason that an automatic engine is able to have different gears at all.
What causes a GMC to not shift gears?
Vehicle won’t move in any gear. Low transmission fluid level – One of the most common issues that prevent a GMC vehicle from shifting when placed in the Drive (D) or Reverse (R) is a low transmission fluid level. Shifter link – The shifter link connects the shifter to the transmission valve body.