Planetary powershifts - 8 & 15 Speed Flashcards
When was the 8 speed planetary powershift transmission introduced by Deere?
The 8 speed planetary powershift transmission was introduced in 1964.
What was notable about the 8 speed planetary powershift transmission?
It was quite revolutionary for its time.
In which tractors was the 8 speed planetary powershift transmission more popular?
It was more popular in lower horsepower tractors such as 3020’s and 4020’s.
Which series of tractors also had powershift transmissions?
Some 30 and 40 series tractors had powershift transmissions.
What was the only transmission option in a 4840 tractor?
In a 4840 tractor, the PST was the only transmission option.
What was a limitation of the 8 speed planetary powershift transmission?
With only 8 speeds, gear selection tended to be a bit limited.
Until when was the 8 speed planetary powershift transmission used?
The 8 speed was used until the introduction of the 50 series.
What transmission was introduced with the 50 series?
The 15 speed planetary PST was introduced.
What percentage of 50, 55, and 60 series tractors were sold with a powershift transmission?
The majority of all 50, 55, and 60 series tractors were sold with a powershift transmission.
What was the only transmission option on all larger models of tractors?
On all larger models, the PST was the only option.
How popular was the planetary powershift transmission designed by Deere?
This design proved to be one of the most popular transmissions built by Deere.
What is the basic layout of the John Deere 8 Speed PST transmission?
The John Deere 8 Speed PST transmission consists of two traction clutches and a multiple compound output planetary.
How many forward and reverse speeds does the John Deere 8 Speed PST transmission provide?
It provides 8 forward speeds and 4 reverse speeds.
What components contribute to the speed variations in the John Deere 8 Speed PST transmission?
The different combinations of brakes and clutches in the planetary pack, plus the engagement of one or both traction clutches.
What is the basic layout of the 8 Speed PST?
The basic layout includes the following positions: C3, B4, B3, B2, B1, PTO, C2, C1.
What is the connection between the engine and the transmission in a torsion dampened disc system?
The only connection to the engine is a single torsion dampened disc.
What feature did early tractors have for transmission control?
Early tractors had a hand operated mechanical linkage.
What was the purpose of the mechanical linkage in early tractors?
It allowed the transmission to be isolated from the engine.
What transmits engine power to the clutch pack assembly?
Engine power is transmitted from the torsional damper to the clutch pack assembly.
How many hydraulically actuated clutches are in the clutch pack?
The clutch pack contains three hydraulically actuated clutches.
Do the clutches in the clutch pack operate together or independently?
All clutches operate independently of each other.
What does the PTO clutch do?
The PTO clutch transmits power to the PTO driveline.
What are the functions of the C1 and C2 clutches?
The C1 & C2 clutch are used for the powershift transmission.
What is the function of the C1 clutch?
C1 is the low range clutch.
What is the function of the C2 clutch?
C2 is the high range clutch.
Can C1 and C2 clutches be engaged separately?
C1 or C2 may be engaged separately, or they may be engaged at the same time depending on selected gear.
What do the shafts exiting from the C1 & C2 clutch become?
The two shafts exiting from the C1 & C2 clutch become the inputs to the planetary pack.
Where is the planetary pack located?
The planetary pack is located in the main section of the transmission and contains additional elements.
What does the planetary pack receive powerflow from?
The planetary pack receives powerflow from the clutch pack.
How many brakes and clutches does the planetary pack contain?
The planetary pack contains four brakes and one clutch.
What are B1 and B2 classified as?
B1 and B2 are classified as reduction brakes.
What is B3 in the planetary pack?
B3 is the reverse brake.
What is B4 in the planetary pack?
B4 is the overdrive brake.
What is C3 in the planetary pack?
C3 is the direct drive clutch.
How are the planet pinions mounted in the planetary pack?
All planet pinions shown are mounted to the same planetary carrier assembly - multiple compound planetary.
What does the output shaft from the planetary pack drive?
The output shaft from the planetary pack drives the differential drive shaft through a reduction gear set.
What is the operating speed of the transmission components?
The operating speed of the transmission components is relatively high to reduce torque loads.
What additional function does the reduction gear set serve?
The reduction gear set also serves as a drop down to align the transmission shaft with the differential.
What are the two main sections of the 8 Speed PST transmission?
The two main sections are the input section and the output section.
What elements make up the input section of the 8 Speed PST transmission?
The input section consists of C1, C2, B1, and B2.
What elements make up the output section of the 8 Speed PST transmission?
The output section consists of B3, B4, and C3.
How many elements are required to complete powerflow in the 8 Speed PST?
Two elements are required from the input section and one from the output section.
What is the role of the compound planetary carrier in the 8 Speed PST?
The compound planetary carrier is the output from the input section and becomes the input to the output section.
How can the input and output sections be visually separated?
A vertical line can be drawn between the B2 and B3 ring gears, with the front half as input and the rear half as output.
How many different input ratios can be provided to the planetary carrier?
A combination of two of the various input elements will provide five different input ratios to the planetary carrier.
What is required to complete powerflow in the 8 Speed PST operation?
One element from the output section must also be used.
In which direction are C3 and B4 used?
C3 and B4 are only used in forward.
What happens when C3 is engaged?
The B3 and B4 sun are locked together.
What is the relationship between the output shaft and the carrier?
The output shaft is ‘locked’ to the carrier - direct drive.
What occurs when B4 is engaged?
The B4 sun is held, and powerflow is transmitted from the carrier, through the compound planet pinions, to the B3 sun gear - overdrive.
When is B3 used?
B3 is only used for reverse.
What happens when B3 is engaged?
The planet pinions in mesh with the ring are forced to rotate in the opposite direction - reverse.
How does power flow move when B3 is engaged?
Power flow is then moved through the double pinions and causes the B3 sun to rotate in the opposite direction of input.
What is common to the first four forward speeds?
C3 is common to the first four forward speeds.
How is the input ratio determined?
The input ratio is determined by using a combination of Cia as well as B1 & B2.
What is the output in 5t?
In 5t, the overdrive output is used with a slower input speed to achieve the desired overall ratio.
What is the output in F6?
In F6, the overdrive output is used along with a little faster input; the overall ratio through the transmission is still an underdrive.
What is the ratio through the transmission in F7?
In F7, the ratio through the transmission is direct drive.
What is the overall trans ratio in F8?
In F8, the overall trans ratio is an overdrive.
What brake is used when any reverse speed is selected?
When any reverse speed is selected, the B3 brake is used.
What is the sequence of input elements used for reverse?
The input elements used for reverse are in the same sequence as the first four forward gears.
How many reverse gears are theoretically available?
Theoretically, the number of reverse gears available is not specified in the provided text.
What type of transmission does the 40 Series John Deere have?
The 40 Series John Deere features an 8-speed powershift transmission.
What is the role of the shift valve in the 40 Series John Deere transmission?
The shift valve provides control of oil flow to and from a variety of main shift valves.
What components are responsible for metering oil flow in the 40 Series John Deere transmission?
A variety of metering orifices/valves and a pair of accumulators are responsible for metering the oil flow.
What is the purpose of metering oil flow in the transmission?
It provides satisfactory shifting during operation.
What will be studied regarding the 40 Series John Deere transmission?
Only a portion of the system will be studied to show the differences and similarities between mechanically controlled systems and electronically controlled systems.
What regulates the pressure oil supplied to the shift valves in 4th speed forward?
Transmission regulated pressure oil is supplied from three locations: the clutch pedal valve, regulated pressure oil from the filter through the accumulator circuits, and regulated pressure oil from the direction valve.
What additional oil is supplied in the 4th speed forward transmission?
Pilot oil from the speed selector valve.
What are the functions of the two accumulators in the system?
They assist with the initial rapid filling of the element and slow down the final engagement of the element.
What controls the speed of element disengagement?
The dump valve.
Where can one find clarification on the oil flow in the system?
Refer to the schematic diagram.
What is the Powershift Transmission Schematic for?
It is for the 40 Series Deere - 8 Speed PST.
What is required to engage a Speed Forward?
Oil low.
What are the elements required for the Powershift Transmission?
02, B3, C3.
What is the role of the accumulator during a shift?
The accumulator helps regulate oil flow and pressure changes during gear shifts.
What happens when a change is made from 1st gear to 2nd gear?
The B1 element must be disengaged and the B2 element must be applied.
What does pilot oil from the speed selector valve do?
It is routed to the B1 B2 shift valve, causing it to move down.
What occurs when there is an open path for oil to flow into the B2 element?
The pressure in the circuit will drop.
What does the drop in pressure cause in the B1 B2 accumulator?
It allows regulated oil and accumulator oil to flow to B2.
What happens after the initial quick fill is complete?
The pressure in the system begins to increase.
What effect does increasing pressure have on the accumulator?
The accumulator shifts to the left, restricting the flow of regulated oil.
How does the B1 B2 accumulator help control engagement speed?
It is being recharged, which helps control the speed of engagement.
What happens to the dump valve when system pressure drops?
The pressure holding the dump valve open is reduced, allowing spring pressure to partially close it.
What is the effect of the dump valve partially closing?
It slows the release of the offcoming element.
What occurs when pressure increases again in relation to the dump valve?
The dump valve is forced to its wide open position, allowing the element to fully disengage.
