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3TZ 994D WHEEL LOADER Operacin de SistemasNmero de publicacin RENR2507-00 Fecha de publicacin 1998/10/01 Fecha deactualizacin 2001/10/02

Transmission

SMCS Code: 3030; 3155; 3160; 3169; 3190

Illustration 34

Transmission Components

(1) Input Shaft

(2) Output Shaft

(3) Hub

Page 1 of 12Copyright 1991, 2003 Caterpillar Inc. All Rights Reserved.

11-04-2003file://C:\SIS\TMP\sisB5A1prt.html


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(4) No. 5 Clutch (First Speed)

(5) No. 4 Carrier

(6) No. 4 Clutch (Second Speed)

(7) No. 3 Sun Gear

(8) No. 3 Clutch (Third Speed)

(9) No. 2 and No. 3 Carrier

(10) No. 2 Clutch (Forward)

(11) No. 2 Sun Gear

(12) No. 1 Clutch (Reverse)

(13) Coupling Gear for No. 1 Clutch

(14) Ring Gear

(15) No. 1 Carrier

(16) No. 1 Sun Gear

(17) No. 1 Planetary Gears

(18) No. 4 Sun Gear


(20) Ring Gear for No. 4 Clutch








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Illustration 35

Clutch Operation

(25) Piston. (26) Spring. (27) Plates. (28) Ring Gear. (29) Discs. (30)Housing.

The transmission has five hydraulically activated clutches that give threespeeds FORWARD and three speeds REVERSE. Speed and direction areselected with the STIC.

The five transmission clutches are located in separate housings. Each clutchhas discs (29) and plates (27). The inside teeth of discs (29) are engagedwith the outside teeth of ring gear (28). Notches on the outside diameter ofplates (27) are engaged with pins in the clutch housing. The pins keep theplates from rotating.

Springs (26) are between clutch housing (30) and piston (25). The springskeep the clutches disengaged. The clutches are engaged when oil is sentinto the area behind piston (25). The piston moves to the right when thepressure of the oil increases. The piston moves against the force of spring(26) and the piston pushes the discs and plates together. The clutch is nowengaged. The discs keep ring gear (28) from rotating. When the clutch isreleased, the pressure in the area behind piston (25) decreases and the forceof spring (26) moves the piston to the left. The discs and the plates are nowaway from each other. The clutch is not engaged.




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A speed clutch and a direction clutch must be engaged simultaneously inorder to send power through the transmission. Table 1 indicates theclutches that are engaged for each forward and each reverse speed.

The transmission is fastened to the transfer case at the center of themachine. Power from the torque converter goes through a drive shaft to the

input transfer gear which drives input shaft (1) of the transmission. Powerflows from the transmission, through output shaft (2) of transmission, andthen to the lower transfer gears.

The No. 1 and No. 2 clutches are located toward the rear of thetransmission. The No. 1 and No. 2 clutches are the direction clutches. TheNo. 1 clutch is the reverse direction clutch. The No. 2 clutch is the forwarddirection clutch.

The No. 3, No. 4, and No. 5 clutches are the speed clutches. The No. 3clutch gives third speed. The No. 4 clutch gives second speed. The No. 5clutch gives first speed.

The only clutch that rotates is the No. five clutch.

Operation

Neutral

When the transmission is in neutral, No. 3 clutch (8) is engaged. Clutch (8)

Table 1

Speed Engaged Clutches

First Speed Forward 2 and 5

Second Speed Forward 2 and 4

Third Speed Forward 2 and 3

Neutral 3

First Speed Reverse 1 and 5

Second Speed Reverse 1 and 4

Third Speed Reverse 1 and 3




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holds ring gear (22) stationary. Ring gear (22) is connected to carrier (9).

Because only No. 3 clutch (8) is engaged, input shaft (1) turns and outputshaft (2) stays stationary.

First Speed Forward

Illustration 36

Power Flow in First Speed Forward

(1) Input Shaft

(2) Output Shaft

(3) Hub





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Input shaft (1) turns Number 2 sun gear (11). The Number 2 sun gear turnsplanetary gears (24). Because ring gear (23) is held stationary by theNumber 2 clutch, planetary gears (24) move around the inside of the ringgear. The movement of planetary gears (24) causes No. 2 carrier (9) andNo. 3 carrier (9) to turn in the same direction as input shaft (1).

As carrier (9) turns, planetary gears (21) turn ring gear (22) and sun gear(7). Sun gear (7) turns output shaft (2).

Ring gear (22) turns carrier (5). Carrier (5) is connected to rotating hub (3)by the engagement of Number 5 clutch (4). This allows power to travelfrom carrier (5) to sun gear (18). The power then travels through Number 5clutch to rotating hub (3). Sun gear (18) and rotating hub (3) are fastened tooutput shaft (2).

As a result, the torque to output shaft (2) is divided between Number 3 sungear (7), Number 4 sun gear (18), and rotating hub (3). From the outputshaft, power travels through the output transfer gears to the differentials.

Second Speed Forward

When the transmission is in SECOND SPEED FORWARD, Number 4clutch (6) and Number 2 clutch (10) are engaged. The Number 2 clutchholds ring gear (23) for the Number 2 clutch stationary. The Number 4clutch holds ring gear (20) for the Number 4 clutch stationary. Input shaft(1) turns Number 2 sun gear (11). Number 2 sun gear turns Number 2planetary gears (24).

Because ring gear (23) is held stationary by the Number 2 clutch, planetarygears (24) move around the inside of the ring gear. The movement ofplanetary gears (24) causes No. 2 carrier (9) and No. 3 carrier (9) to turn in

the same direction as input shaft (1). As the Number 2 carrier and theNumber 3 carrier turn, Number 3 planetary gears (21) turn. The Number 2planetary gears turn ring gear (22) for the Number 3 clutch and Number 3sun gear (7). Number 3 sun gear (7) turns output shaft (2). Ring gear (22)turns Number 4 carrier (5).

Because ring gear (20) is held stationary by the Number 4 clutch, planetarygears (19) move around the inside of the ring gear. The movement ofplanetary gears (19) causes Number 4 sun gear (18) to turn. The Number 4sun gear turns output shaft (2).




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As a result, the torque to output shaft (2) is divided between Number 3 sungear (7) and Number 4 sun gear (18). From the output shaft, power travelsthrough the output transfer gears to the differentials.

Third Speed Forward

When the transmission is in THIRD SPEED FORWARD, Number 3 clutch(8) and Number 2 clutch (10) are engaged. The Number 2 clutch holds ringgear (23) for the Number 2 clutch stationary. The Number 3 clutch holdsring gear (22) for the Number 3 clutch stationary. Input shaft (1) turnsNumber 2 sun gear (11). Number 2 sun gear turns Number 2 planetarygears (24).

Because ring gear (23) is held stationary by the Number 2 clutch, planetary

gears (24) move around the inside of the ring gear. The movement ofplanetary gears (24) causes No. 2 carrier (9) and No. 3 carrier (9) to turn inthe same direction as input shaft (1).

The movement of No. 2 carrier (9) and No. 3 carrier (9) causes Number 3planetary gears (21) to move around the inside of ring gear (22) becausering gear (22) is held stationary by the Number 3 clutch. The movement ofplanetary gears (21) causes Number 3 sun gear (7) to turn. The Number 3

sun gear turns output shaft (2). From the output shaft, power travelsthrough the output transfer gears to the differentials.

First Speed Reverse




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Illustration 37

Power Flow in First Speed Reverse

(1) Input Shaft

(2) Output Shaft

(3) Hub


(5) No. 4 Carrier

(6) No. 4 Clutch (Second Speed)

(7) No. 3 Sun Gear




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(8) No. 3 Clutch (Third Speed)

(9) No. 2 and No. 3 Carrier

(10) No. 2 Clutch (Forward)

(11) No. 2 Sun Gear

(12) No. 1 Clutch (Reverse)

(13) Coupling Gear for No. 1 Clutch

(14) Ring Gear

(15) No. 1 Carrier

(16) No. 1 Sun Gear


(18) No. 4 Sun Gear







When the transmission is in FIRST SPEED REVERSE, Number 5 clutch(4) and Number 1 clutch (12) are engaged. The Number 1 clutch holdscoupling gear (13) stationary. The Number 5 clutch connects rotating hub(3) and Number 4 carrier (5).

Input shaft (1) turns Number 1 sun gear (16). The Number 1 sun gear turnsplanetary gears (17). Number 1 carrier (15) is a direct mechanicalconnection with coupling gear (13). Because coupling gear (13) is held

stationary by the Number 1 clutch, Number 1 carrier (15) is also heldstationary. The movement of Number 1 planetary gears (17) causes ring




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gear (14) to turn in the opposite direction as input shaft (1). Ring gear (14)is a direct mechanical connection with carrier (9).

As carrier (9) turns, planetary gears (21) turn ring gear (22) and sun gear(7). Sun gear (7) turns output shaft (2).

Ring gear (22) turns carrier (5). Carrier (5) is connected to rotating hub (3)by the engagement of the Number 5 clutch. This allows power to travelfrom carrier (5) to sun gear (18). The power then travels through theNumber 5 clutch to rotating hub (3). Sun gear (18) and rotating hub (3) arefastened to output shaft (2).

As a result, the torque to output shaft (2) is divided between Number 3 sungear (7), Number 4 sun gear (18), and rotating hub (3). From the output

shaft, power travels through the output transfer gears to the differentials.

Second Speed Reverse

When the transmission is in SECOND SPEED REVERSE, Number 4clutch (6) and Number 1 clutch (12) are engaged. The Number 1 clutchholds coupling gear (13) stationary. The Number 4 clutch holds ring gear(20) for the Number 4 clutch stationary. Input shaft (1) turns Number 1 sungear (16). The Number 1 sun gear turns Number 1 planetary gears (17).Number 1 carrier (15) is a direct mechanical connection with coupling gear(13).

Because coupling gear (13) is held stationary by the Number 1 clutch,Number 1 carrier (15) is also held stationary. The movement of Number 1planetary gears (17) causes ring gear (14) to turn in the opposite directionas input shaft (1). Ring gear (14) is a direct mechanical connection withcarrier (9). As the Number 2 carrier and the Number 3 carrier turn, Number

3 planetary gears (21) turn. The Number 3 planetary gears turn ring gear(22) for the Number 3 clutch and Number 3 sun gear (7). Number 3 sungear (7) turns output shaft (2). Ring gear (22) turns Number 4 carrier (5).

Because ring gear (20) is held stationary by the Number 4 clutch, planetarygears (19) move around the inside of the ring gear. The movement ofplanetary gears (19) causes Number 4 sun gear (18) to turn. The Number 4sun gear turns output shaft (2).

As a result, the torque to output shaft (2) is divided through Number 3 sungear (7) and Number 4 sun gear (18). From the output shaft, power travels




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through the output transfer gears to the differentials.

Third Speed Reverse

When the transmission is in THIRD SPEED REVERSE, Number 3 clutch

(8) and Number 1 clutch (12) are engaged. The Number 1 clutch holdscoupling gear (13) stationary. The Number 3 clutch holds ring gear (22)stationary. Input shaft (1) turns Number 1 sun gear (16). Number 1 sun gearturns Number 1 planetary gears (17). Number 1 carrier (15) is a directmechanical connection with coupling gear (13).

Because coupling gear (13) is held stationary by the Number 1 clutch,Number 1 carrier (15) is also held stationary. The movement of Number 1planetary gear (17) causes ring gear (14) to turn in the opposite direction as

input shaft (1). Ring gear (14) is a direct mechanical connection withcarrier (9).

The movement of carrier (9) causes Number 3 planetary gears (21) to movearound the inside of the ring gear. This occurs because ring gear (22) isheld stationary by the Number 3 clutch. The movement of planetary gears(21) causes Number 3 sun gear (7) to turn. The Number 3 sun gear turnsoutput shaft (2). From the output shaft, power travels through the output

transfer gears to the differentials.Copyright 1991, 2003 Caterpillar Inc.All Rights Reserved.


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