Automatic Transaxle (F4A42)
AUTOMATIC TRANSAXLE SYSTEMDESCRIPTION
The automatic transmission is a combination of 3-element 2-phase 1 -stage torque converter and double shaft electrically-controlled unit which provides 4 speeds forward and 1 reverse. The entire unit is in line with the engine.
CHARACTERISTICS
HIVEC: Hyundai Intelligent Vehicle Electronic Control
It differs drastically compared to previous T/M such as alpha, Beta or KM series automatic transaxles. All vehicles adopted with an engine volume of 2.0 liters or more has the HIVEC automatic transaxle developed and produced by Hyundai.
Some of the characteristics include:
^ Different power transfer
^ Different component layout
^ New shift logic (HIVEC) to improve shift feeling
^ Position of Valve Body
^ Variable shift pattern
^ Communication protocol and method
MECHANICAL SYSTEM
OPERATION COMPONENTS AND FUNCTION
OPERATION COMPONENTS AND FUNCTION:
OPERATING ELEMENTS
OPERATING ELEMENTS:
TORQUE CONVERTER AND SHAFT
The torque converter consists of a impeller (pump), turbine and stator assembly in a single unit. The pump is connected to the engine crankshaft and turns as the engine turns. This drawing force is transmitted to the turbine through the oil which is recycled by the stator.
The transmission has two parallel shafts; the input shaft and the output shaft. Both shafts are in line with the engine crankshaft. The input shaft includes the overdrive clutch, reverse clutch, underdrive clutch, one way clutch, 2ND brake, low reverse brake, overdrive planetary carrier, output planetary carrier and transfer drive gear. The output shaft includes the transfer driven gear.
CLUTCHES
The gear changing mechanism utilizes three multi-disc clutches. The retainers of these clutches are fabricated from high-precision sheet metal for lightness and ease of production. Also, more responsive gearshifts at high engine speeds are achieved by a pressure-balanced piston mechanism that cancels out centrifugal hydraulic pressure. This mechanism replaces the conventional ball check-valve.
UNDERDRIVE CLUTCH
The underdrive clutch operates in 1st, 2nd, and 3rd gears and transmits driving force from the input shaft to the underdrive sun gear (A).
The components comprising the under clutch are as illustrated.
Hydraulic pressure acts in the piston pressure chamber (B) (between the piston (c) and retainer) and thus pushes the piston (C). In turn, the piston depresses the clutch discs and thereby transmits driving force from the retainer (D) to the hub (E) side.
At high speed, fluid remaining in the piston pressure chamber is subjected to centrifugal force and attempts to push the piston.
However, fluid in the balance fluid chamber (A) (the space between the piston and return spring retainer (B)) is also subjected to centrifugal force.
Thus, the hydraulic pressure on one side of the piston cancels out the hydraulic pressure on the other side, and the piston does not move.
REVERSE CLUTCH AND OVERDRIVE CLUTCH
The reverse clutch (c) operates when the reverse gear is selected and transmits driving force from the input shaft to the reverse sun gear.
The overdrive clutch (D) operates in 3rd and 4th gears and transmits driving force from the input shaft to the overdrive planetary carrier and low-reverse annulus gear.
BRAKES
The gear changing mechanism utilizes two multi-disc brakes.
LOW-REVERSE BRAKE AND SECOND BRAKE
The low-reverse brake (A) operates in 1st and reverse gears, when the vehicle is parked, and during manual operation. It locks the low-reverse annulus gear and overdrive planetary carrier to the case.
The second (c) brake (B) operates in 2nd and 4th gears and locks the reverse sun gear (D) to the case. The components comprising the low-reverse brake and second brake are as illustrated.
As shown, the discs and plates of the two brakes are arranged on either side of the rear cushion plate (E), which is itself secured to the case (F) by a snap ring.
OWC
To improve the shift feeling from 1st to 2nd gear, OWC was adopted on the Low reverse brake annulus gear. Instead of hydraulic fixing by Low reverse brake at the 1st gear, this mechanical fixing device was used. This structure is not new concept, because this OWC already has been installed on the:
ACCUMULATORS
ACCUMULATORS:
OBJECTIVE
^ Energy (hydraulic pressure) storage
^ Impact and pulsation damping when solenoid valves operating
^ Operation as spring element
^ Smooth shifting by preventing sudden operation of clutches and brakes
TRANSFER DRIVE GEAR
With the transfer drive gear, increased tooth height and a higher contact ratio have reduced gear noise.
Also, the bearing that supports the drive gear is a preloaded type that eliminates rattle, and the rigidity of the gear mounting has been increased by bolting the bearing directly onto the case.
OUTPUT SHAFT/TRANSFER DRIVEN GEAR
As shown in the illustration, the transfer driven gear is press-fitted onto the output shaft, and the output shaft is secured by a locking nut and supported by bearings. The locking nut has a left-handed thread, and a hexagonal hole in the other end of the shaft enables the shaft to be held in position for locking nut removal.
MANUAL CONTROL SYSTEM
MANUAL CONTROL LEVER
The manual control lever is fitted to the top of the valve body and is linked to the parking roller rod and manual control valve pin.
A detent mechanism is provided to improve the gear shift feeling during manual selection.
PARKING MECHANISM
When the manual control lever is moved to the parking position, the parking roller rod moves along the parking roller support and pushes up the parking sprag. As a result, the parking sprag meshes with the transfer driven gear (parking gear), thereby locking the output shaft. To minimize the operating force required, a roller is fitted to the end of the rod.
POWER TRAIN
P POSITION
Hydraulic pressure is applied to the LR brake and the RED brake, so power is not transmitted from the input shaft to the LID clutch or OD clutch, and the output shaft is locked by the park brake pawl interlocking the park gear.
N POSITION
Hydraulic pressure is applied to the LR brake (A) and the RED brake, so power is not transmitted from the input shaft to the UD clutch or OD clutch.
1ST GEAR POWER FLOW
Hydraulic pressure is applied to the UD clutch (B) the LR brake (A) and the one way clutch (OWC), then the LID clutch transmits driving force from the input shaft to the LID sun gear, and the LR brake locks the LR annulus gear to the case. The LID sun gear of the planetary gear drives the output pinion gear, and the LR brake locks the annulus gear, and the output pinion drives the output carriers, and the output carrier drives the transfer drive gear, and the transfer drive gear drives the transfer driven gear of the output shaft, and power is transmitted to the differential gear through the differential drive gear.
2ND GEAR POWER FLOW
Hydraulic pressure is applied to the UD clutch (A) the 2nd brake (B) and the one way clutch (OWC), then the LID clutch transmits driving force from the input shaft to the LID sun gear, and the 2nd brake locks the reverse sun gear to the case. The UD sun gear of the planetary gear drives the output pinion gear and the LR annulus gear, and the LR annulus gear drives the OD planetary carriers, and OD planetary carriers drives OD pinion gear, and the OD pinion gear drives the output carriers, and the output carrier drives the transfer drive gear, and the transfer drive gear drives the transfer driven gear of the output shaft, and power is transmitted to the differential gear through the differential drive gear.
3RD GEAR POWER FLOW
Hydraulic pressure is applied to the UD clutch (A) and the OD clutch (B), then the UD clutch transmits driving force from the input shaft to the LID sun gear, and the OD clutch transmits driving force from the input shaft to the overdrive planetary carrier and low-reverse annulus gear. The UD sun gear of the planetary gear drives the output pinion gear and the LR annulus gear, and the LR annulus gear drives the OD pinion gear through the OD planetary carrier, and the OD pinion gear drives the reverse sun gear and the output carrier. The OD clutch drives the OD carrier, and the OD carrier drives the OD pinion gear, and the OD pinion gear drives the reverse sun gear and the output carrier, and the output carrier drives the transfer drive gear, and the transfer drive gear drives the transfer driven gear of the output shaft, and power is transmitted to the differential gear through the differential drive gear.
4TH GEAR POWER FLOW
Hydraulic pressure is applied to the OD clutch (A) and the 2nd brake (B), then the OD clutch transmits driving force from the input shaft to the OD planetary carrier and LR annulus gear, and the 2nd brake locks the reverse sun gear to the case. The OD clutch drives the OD carrier, and the OD carrier drives the OD pinion gear and the LR annulus gear, and the OD pinion gear drives the output carrier, and the output carrier drives the transfer drive gear, and the transfer drive gear drives the transfer driven gear of the output shaft, and power is transmitted to the differential gear through the differential drive gear.
REV GEAR POWER FLOW
Hydraulic pressure is applied to the reverse clutch (A) and the LR brake (B), then the reverse clutch transmits driving force from the input shaft to the reverse sun gear, and the LR brake locks the LR annulus gear and OD planetary carrier to the case. The reverse clutch drives the reverse sun gear, and the reverse sun gear drives the output carrier through the OD pinion gear, and the output carrier drives the transfer drive gear, and the transfer drive gear drives the transfer driven gear of the output shaft, and power is transmitted to the differential gear through the differential drive gear.
HYDRAULIC CONTROL SYSTEM
HYDRAULIC CONTROL SYSTEM DESCRIPTION:
DESCRIPTION
^ Better and smoother shift quality.
^ In order to prevent ATF leakage from the valve body or each elements, the exhaust ports have been grouped into only one with an addition of a checkball.
^ If a failure occurs in its electric control, the switch valve and fall safe valve is able to move to enable 3rd speed drive or reverse. The hydraulic system consists of oil pump, regulator valve, solenoid valves, pressure control valve and valve body
OPERATION COMPONENTS AND FUNCTIONS
Oil Pump
The oil pump is made of aluminum to reduce its weight. The oil pump is not a serviceable part; it must be replaced as a pump assembly
Do not disassemble the pump as improper alignment during assembly will cause pump failure and could cause damage to the transaxle.
When removing the oil pump from the T/M case, the S.S.T. (09452-33100) must be used.
OPERATION OF EACH VALVE
Torque converter pressure control valve: The function of this valve is to maintain a constant pressure within the torque converter.
Damper clutch control valve: Its function is to control the hydraulic pressure that acts on the Damper Clutch. Manual valve: The position of the manual valve is determined by the selector lever and applies or cuts line pressure to different valves.
Pressure control valve & Solenoid valve: The pressure control valve prevents a rapid decrease in hydraulic pressure when the clutch becomes disengaged. It also reduces the sharp increase in input shaft speed during clutch to clutch control.
Switch valve: When the OD clutch is applied, the hydraulic pressure is applied to the regulator valve via the switch valve. Hence, the line pressure is reduced at 3rd and 4th gear.
Fail Safe Valve-A: During fail safe mode, this valve releases the pressure in the LR Brake.
Fail Safe Valve-B: During fail safe mode, this valve cuts the pressure from the 2nd pressure control valve to 2nd brake.
HYDRAULIC FLOW
P AND N POSITION
The TCM controls the solenoid valves. The conditions of the solenoid valve and positions of the solenoid valve are as follows:
^ The LR solenoid valve is turned off, and the LR pressure solenoid valve is moved to the left-side.
^ The 2nd solenoid valve is turned on, and the 2nd pressure solenoid valve remains in the right-side.
^ The UD solenoid valve is turned on, and the UD pressure solenoid valve remains in the right-side.
^ The OD solenoid valve is turned on, and the OD pressure solenoid valve remains in the right-side.
^ The line pressure is supplied to the regulator valve and the fail-safe valve A.
^ The line pressure is supplied to each element (fail-safe valve B, switch valve, DCCV, LR solenoid valve, LR pressure control valve).
^ The fail-safe valve B moves to the left side by the line pressure through the manual valve.
^ The switch valve moves to the left side by the line pressure. The line pressure is supplied to the DCCV, and DCCV moves to the right-side.
^ The line pressure is supplied to the LR pressure control valve and the LR solenoid valve, and TCM turns off the LR solenoid valve, so the line pressure is supplied to the LR brake through the switch valve and the fail-safe valve A.
^ The regulator valve moves to the left side by the line pressure through the manual valve, and the line pressure is supplied to the torque converter pressure control valve and the oil pump.
D POSITION: 1ST GEAR
The TCM controls the solenoid valves. The conditions of the solenoid valve and positions of the solenoid valve are as follows:
^ The LR solenoid valve is turned off, and the LR pressure solenoid valve is moved to the left-side.
^ The 2nd solenoid valve is turned on, and the 2nd pressure solenoid valve remains in the right-side.
^ The UD solenoid valve is turned off, and the UD pressure solenoid valve is moved to the left-side.
^ The OD solenoid valve is turned on, and the OD pressure solenoid valve remains in the right-side.
^ The line pressure is supplied to the regulator valve and the fail-safe valve A.
^ The line pressure is supplied to each element (fail-safe valve B, switch valve, damper clutch control valve, LR solenoid valve, LR pressure control valve).
^ The line pressure through the manual valve is supplied to each element (DCCV, 2nd solenoid valve, 2nd pressure control valve, OD solenoid valve, OD pressure control valve, UD solenoid valve, UD pressure control valve).
^ The fail-safe valve B moves to the left side by the line pressure.
^ The switch valve moves to the left side by the line pressure.
^ The line pressure is supplied to the DCCV, and TCM turns off the DCCSV, so the DCCV remains in the right side
^ The line pressure is supplied to the LR pressure control valve and the LR solenoid valve, and TCM turns off the LR solenoid valve, so the line pressure is supplied to the LR brake through the switch valve and the fail-safe valve A.
^ The line pressure is supplied to the UD pressure control valve and the UD solenoid valve, and TCM turns off the UD solenoid valve, so the line pressure is supplied to the UD clutch and the fail-safe valve B.
^ The regulator valve moves to the left side by the line pressure through the manual valve, and the line pressure is supplied to the torque converter pressure control valve and the oil pump.
D POSITION: 2ND GEAR
The TCM controls the solenoid valves. The conditions of the solenoid valve and positions of the solenoid valve are as follows:
^ The LR solenoid valve is turned on, and the LR pressure solenoid valve remains in the right-side.
^ The 2nd solenoid valve is turned off, and the 2nd pressure solenoid valve is moved to the left-side.
^ The UD solenoid valve is turned off, and the LID pressure solenoid valve is moved to the left-side.
^ The OD solenoid valve is turned on, and the OD pressure solenoid valve remains in the right-side.
^ The line pressure is supplied to the regulator valve and the fail-safe valve A.
^ The line pressure is supplied to each element (fail-safe valve B, switch valve, damper clutch control valve, LR solenoid valve, LR pressure control valve).
^ The line pressure through the manual valve is supplied to each element (DCCV, 2nd solenoid valve, 2nd pressure control valve, OD solenoid valve, OD pressure control valve, UD solenoid valve, UD pressure control valve).
^ The fail-safe valve B moves to the right side by the line pressure through 2nd pressure control valve and the line pressure through the LID pressure control valve. The pressure through the manual valve is supplied to the fail-safe valve A, and the fail-safe valve A moves to the left side
^ The switch valve moves to the left side by the line pressure. The line pressure is supplied to the DCCV and the DCCSV, and TCM turns off the DCCSV, so the DCCV remains in the right side
^ The line pressure is supplied to the 2nd pressure control valve and the 2nd solenoid valve, and TCM turns off the 2nd solenoid valve, so the line pressure is supplied to the 2nd brake and the fail-safe valve A through the fail-safe valve B.
^ The line pressure is supplied to the UD pressure control valve and the UD solenoid valve, and TCM turns off the UD solenoid valve, so the line pressure is supplied to the UD clutch and the fail-safe valve B. The regulator valve moves to the left side by the line pressure through the manual valve, and the line pressure is supplied to the torque converter pressure control valve and the oil pump.
D POSITION: 3RD GEAR
The TCM controls the solenoid valves. The conditions of the solenoid valve and positions of the solenoid valve are as follows:
^ The LR solenoid valve is turned on, and the LR pressure solenoid valve remains in the right-side.
^ The 2nd solenoid valve is turned on, and the 2nd pressure solenoid valve remains in the right-side.
^ The UD solenoid valve is turned off, and the UD pressure solenoid valve is moved to the left-side.
^ The OD solenoid valve is turned off, and the OD pressure solenoid valve is moved to the left-side.
^ The line pressure is supplied to the regulator valve and the fail-safe valve A.
^ The line pressure is supplied to each element (fail-safe valve B, switch valve, DCCV, LR solenoid valve, LR pressure control valve).
^ The line pressure through the manual valve is supplied to each element (DCCSV, 2nd solenoid valve, 2nd pressure control valve, OD solenoid valve, OD pressure control valve, UD solenoid valve, UD pressure control valve).
^ The fail-safe valve B moves to the right side by the line pressure through the UD pressure control valve and the line pressure through the OD pressure control valve. The pressure is supplied to the fail-safe valve A through the OD pressure control valve, but the fail-safe valve A does not move to the right side
^ The line pressure is supplied to the DCCV and the DCCSV, and TCM turns on the DCCSV, and the DCCV moves to the left side, and the damper clutch is operated.
^ The line pressure is supplied to the UD pressure control valve and the UD solenoid valve, and TCM turns off the UD solenoid valve, so the line pressure is supplied to the UD clutch and the fail-safe valve B.
^ The line pressure is supplied to the OD pressure control valve and the OD solenoid valve, and TCM turns off the OD solenoid valve, so the line pressure is supplied to the OD clutch and the fail-safe valve A/B and the switch valve.
^ The switch valve moves to the right side by the line pressure through the OD pressure control valve.
^ The regulator valve moves to the left side by the pressure through the manual valve and the pressure through the switch valve, and the line pressure is more supplied to the oil pump.
D POSITION: 4TH GEAR
The TCM controls the solenoid valves. The conditions of the solenoid valve and positions of the solenoid valve are as follows:
^ The LR solenoid valve is turned on, and the LR pressure solenoid valve remains in the right-side.
^ The 2nd solenoid valve is turned off, and the 2nd pressure solenoid valve is moved to the left-side. The UD solenoid valve is turned on, and the UD pressure solenoid valve remains in the right-side.
^ The OD solenoid valve is turned off, and the OD pressure solenoid valve is moved to the left-side.
^ The line pressure through the manual valve is supplied to the regulator valve and the fail-safe valve A. The line pressure is supplied to each element (fail-safe valve B, switch valve, DCCV, LR solenoid valve, LR pressure control valve).
^ The line pressure through the manual valve is supplied to each element (DCCSV, 2nd solenoid valve, 2nd pressure control valve, OD solenoid valve, OD pressure control valve, UD solenoid valve, UD pressure control valve).
^ The fail-safe valve B moves to the right side by the line pressure through the 2nd pressure control valve and the line pressure through the OD pressure control valve.
^ The line pressure through the OD pressure control valve is supplied to the fail-safe valve A, and the fail-safe valve A moves to the right side by the line pressure through the fail-safe valve B and the line pressure through the OD pressure control valve.
^ The line pressure is supplied to the DCCV and the DCCSV, and TCM turns on the DCCSV, so DCCV moves to the right side, and the damper clutch is operated.
^ The line pressure is supplied to the OD pressure control valve and the OD solenoid valve, and TCM turns off the OD solenoid valve, so the line pressure is supplied to the OD clutch and the fail-safe valve A/B and the switch valve.
^ The line pressure is supplied to the 2nd pressure control valve and the 2nd solenoid valve, and TCM turns off the 2nd solenoid valve, so the line pressure through the 2nd pressure control valve is supplied to the 2nd brake through the fail-safe valve B.
^ The regulator valve moves to the left side by the line pressure through the manual valve and the line pressure through the switch valve, and the line pressure is more supplied to the oil pump.
REVERSE POSITION
The TCM controls the solenoid valves. The conditions of the solenoid valve and positions of the solenoid valve are as follows:
^ The LR solenoid valve is turned off, and the LR pressure solenoid valve is moved to the left-side.
^ The 2nd solenoid valve is turned on, and the 2nd pressure solenoid valve remains in the right-side.
^ The UD solenoid valve is turned on, and the UD pressure solenoid valve remains in the right-side.
^ The OD solenoid valve is turned on, and the OD pressure solenoid valve remains in the right-side.
^ The line pressure through the manual valve is supplied to the reverse clutch and the fail-safe valve B.
^ The line pressure is supplied to each element (fail-safe valve B, switch valve, DCCV, LR solenoid valve, LR pressure control valve).
^ The fail-safe valve B moves to the left side by the line pressure.
^ The switch valve moves to left side by the line pressure, and the line pressure through the LR pressure control valve is supplied to the LR brake through the fail-safe valve A.
^ The line pressure is supplied to the DCCV, so the DCCV remains in the right-side. The fail-safe valve A moves to the right side by the line pressure through the switch valve.
^ The line pressure is supplied to the LR pressure control valve and the LR solenoid valve, and TCM turns off the LR solenoid valve, and the line pressure is supplied to the LR brake through the LR pressure control valve and the switch valve and the fail-safe valve A.
^ The regulator valve moves to the right side by the no line pressure through the manual valve, and the line pressure is higher than other range.