hydraulic fun damentals · hydraulic fun‐damentals introduction learning how to read and...
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Presented by:Bill Brayton
ATRA Senior Research Technician
Hydraulic Fun‐damentals
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Hydraulic Fun‐damentals
IntroductionLearning how to read and interpret oil schematics is one of the keys to being able to understand hydraulic functions of an automatic transmission and project the outcome of a targeted modification. Another part of this understanding is the effect valve size and spring tension have on the various valves.
This webinar is designed to help you:
1. Understand valve functions.2. Develop the skills for reading oil schematics, so you can isolate the valves responsible for a given function or malfunction and address it with a targeted modification that will offer the results you’re looking for.
Hydraulic Fun‐damentals
Valve Types1. Regulator: A regulator valve lowers pressure from a higher‐pressure source. A regulator can
have a static setting, producing a constant value of pressure; or it can vary the pressure output, based on the influences from mechanical force or hydraulic pressure.
2. Switch: A switch valve works like a light switch; it’s either on or off. It supplies a component or another valve with oil, or it exhausts the oil to the sump. The most common valve of this type is a shift valve. It can direct oil to a shifting element, like a servo or clutch drum; or it can switch oil pressure between two other valves. Many PWM regulators are really switch valves that open and close so quickly they actually operate as a regulator; but the valve is still considered a switch.
3. Servo: A servo valve moves another valve; either a switch valve or regulator valve.
Hydraulic Fun‐damentalsRegulator Valves
One of the first exercises in understanding valve function and oil schematic interpretation is identifying the three types of valves. The regulator valve is the most common, but the most difficult to recognize because there are several types of regulators. There are two properties common to all regulators that will help you identify them:
1. Nearly all regulators use a spring 2. Source pressure is used to move the vale toward the spring
All regulators require a balance system to maintain regulation. Most balance systems take pressure that the regulator has modified and uses it on an area of the regulator. This balance pressure works on the valve to move it toward the spring.
In these examples, there are three basic regulators. In the first example, the balance oil is regulated pressure that is diverted to the end of the valve.
Balance Pressure
Mainline(source pressure)
Regulated Pressure
Hydraulic Fun‐damentalsRegulator Valves (continued)
Regulator Valve with Internal Balance
The second regulator uses an internal balance system: Pressure isn’t diverted to the end of the valve; instead, the pressure goes between two of the lands on the valve. Since the land closer to the spring is larger, the force created by hydraulic pressure pushes the valve toward the spring.
Hydraulic Fun‐damentalsRegulator Valves (continued)
Regulator Valve with External Balance
The third type of regulator is a main pressure regulator, which operates by bleeding off pressure directly from the pump feed to maintain a balanced pressure.The source pressure for the main pressure regulator originates from the pump, rather than a regulated source. These main pressure regulators use mainline pressure to provide balance pressure. This prevents the entire system from exceeding the level set for the system.
Hydraulic Fun‐damentalsSwitch Valves
Switch valves, as their name implies, switch oil on or off. They can direct oil to a shifting element or another valve.
Switch valves don’t vary pressure like a regulator; they’re either open or closed. Typically, when a switch valve closes a circuit, it will also open that circuit to exhaust.
There is one property of a switch valve that makes it easy to identify: A switch valve doesn’t use source pressure to move the valve. There’s always some other force that moves the valve.
In the next two examples, there are two basic switch valves. In the first example the valve is controlled mechanically. This would be used as a manual valve or detent valve. In the second example, the switch valve is controlled by some other pressure. This arrangement is commonly used for shift valves.
Switch Valve with Mechanical Link
Hydraulic Fun‐damentalsSwitch Valves (continued)
Switch Valve without Mechanical Link
Hydraulic Fun‐damentalsServo Valves
Servo valves serve one main purpose: To move other valves. But sometimes a manufacturer will also use a servo valve as regulator or a switch. You may want to consider these combination valves. A combination valve then can be referred to as a servo/switch valve, or a servo/regulator valve; but its primary function is a servo valve. The next three illustrations are of servo valves.
6L80E
Bumper Spring
4L60E
Hydraulic Fun‐damentalsServo Valves (continued
Servo/Switch Valve
RE5R05A TCC Control Valve
Hydraulic Fun‐damentalsServo Valves (continued)
Hydraulic Fun‐damentals
Switch Valves that Regulate Pressure
Many units today control line pressure using a pulse width modulated solenoid. These solenoids open and close very quickly, which regulates the pressure applied to one side of a switch valve. This causes the switch valve to float between wide open and full closed, regulating the pressure to the circuit. Even though these valve regulate pressure, they’re still considered switch valves.
Hydraulic Fun‐damentals
Switch Valves that Regulate Pressure (continued)
Here the solenoid is receiving a pulsed signal. These pulses are so fast, they cause the switch valve to float between open and closed, causing the valve to work as a regulator.
Hydraulic Fun‐damentals4L60E Pressure Regulator Valve
Components and Line Pressure Rise
Regulator Valve
Servo Valve
A
Pressure Regulators
Hydraulic Fun‐damentalsPressure Regulators(continued) 604 Pressure Regulator
Reverse Position
Hydraulic Fun‐damentalsPressure Regulators(continued)
62TE/41TE VLPS
What is the purpose of the solenoid?
Hydraulic Fun‐damentalsPressure Regulators(continued) Honda Pressure Regulator
Honda’s operate at a constant pressure.How does line pressure rise happen?
A
Line Pressure increases when the stator tube twists with torque. This increases the spring weight which raises line pressure.
Hydraulic Fun‐damentalsPressure Regulators(continued)
6R60/80 Pressure Regulator
Hydraulic Fun‐damentalsShift Feel
The 1‐2 and 3‐4 accumulator assemblies help cushion the 2‐4 band apply rate. These assemblies use an accumulator fluid pressure to assist spring force. Accumulator fluid pressure is regulated by the accumulator valve in relation to torque signal fluid pressure. The pressure control (PC) solenoid is controlled by the PCM and regulates torque signal fluid pressure in relation to engine torque, throttle position and other vehicle operating conditions.When engine torque is a maximum, a greater apply pressure is required to prevent the band from slipping during apply and hold the band against the reverse input housing. When engine torque is a minimum, the band requires less apply force and a slower apply rate. The regulating action of the accumulator valve compensates for these various operating conditions by increasing accumulator fluid pressure as engine torque and torque signal fluid pressure increase.
1‐2 and 3‐4 ACCUMULATOR ASSEMBLIES Accumulator Valve Function
4L60E
Hydraulic Fun‐damentalsShift Feel
4R100Use the previous page valve description to identify the operation of this accumulator system.
Hydraulic Fun‐damentalsShift Feel
BYBA
1st Gear Steady State
All shift solenoids are on.
Hydraulic Fun‐damentalsShift Feel
BYBA
Inbetween 1st and 2nd Gear
The Clutch Pressure Control (CPC) solenoids control the apply and release rate of the clutches. This is how shift feel is controlled.
Shift solenoids still on.
Hydraulic Fun‐damentalsShift Feel
BYBA
2nd Gear Steady State
To finish the shift process shift solenoid C turns off and moves shift valve C to connect line pressure to the 2ndclutch.
Hydraulic Fun‐damentalsShift Feel
In between 4th & 5th.Notice that both CPC solenoids and valves are working to apply and release the clutches.
BYBA
As part of the H1 Fundamental testing you will be asked to identify all the valves in a valve body. Using the illustration on the next page we will go over the various valves and valve types.This will be a part of the H1 hydraulic fundamentals test.
RV = Regulator ValveSWV = Switch valveSV = Servo Valve
Hydraulic Fun‐damentals
Hydraulic Fun‐damentals4R70W
RVRVRV
SWVRV
SWV
RV
SWV
SWV
SWV
RVSWV
SVRV
SV
SWV
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