992K Wheel Loader and 854K Wheel Dozer Power Train Caterpillar


Transmission Planetary

Usage:

992K 880


Illustration 1g01463407
Transmission Components
(1) Coupling gear
(2) Number 1 clutch
(3) Number 2 and Number 3 carrier
(4) Number 2 clutch
(5) Number 2 clutch ring gear
(6) Number 2 sun gear
(7) Number 3 clutch
(8) Number 3 clutch ring gear
(9) Number 3 sun gear
(10) Number 4 clutch
(11) Number 4 clutch ring gear
(12) Number 4 sun gear
(13) Number 5 clutch
(14) Rotating hub
(15) Number 4 carrier
(16) Number 1 carrier
(17) Number 1 sun gear
(18) Input shaft
(19) Number 1 planetary gears
(20) Number 1 clutch ring gear
(21) Number 2 planetary gears
(22) Number 3 planetary gears
(23) Number 4 planetary gears
(24) Output shaft

The transmission is fastened between the input transfer gear case and the output transfer gear case. Input power to the transmission comes from the input transfer gears.

The transmission has five hydraulically activated clutches that provide three forward speeds and three reverse speeds. Speed and direction are selected by moving switches on the STIC. The Number 1 clutch and the Number 2 clutch are the closest clutches to the input end of the transmission. These two clutches are the direction clutches. The Number 1 clutch is the Reverse direction clutch. The Number 2 clutch is the Forward direction clutch.

The Number 3 clutch (7), the Number 4 clutch (10), and the Number 5 clutch (13) are the speed clutches. The Number 3 clutch provides the Third speed. The Number 4 clutch provides the Second speed. The Number 5 clutch provides the First speed.

The Number 5 clutch is the only clutch that rotates when the clutch is engaged.

A speed clutch must be engaged first and a direction clutch must then be engaged so that power may be sent through the transmission. The table provides the combination of the clutches for each forward speed and for each reverse speed.

Table 1
Speed Range and Direction  Energized Solenoids  Engaged Clutches 
Third Speed Forward  3 and 2  3 and 2 
Second Speed Forward  4 and 2  4 and 2 
First Speed Forward  5 and 2  5 and 2 
Neutral 
First Speed Reverse  5 and 1  5 and 1 
Second Speed Reverse  4 and 1  4 and 1 
Third Speed Reverse  3 and 1  3 and 1 

First Speed Forward



Illustration 2g01463527
Power Flow in First Speed Forward with the Number 2 Clutch and the Number 5 Clutch Engaged.
(3) Number 2 and Number 3 carrier
(4) Number 2 clutch
(5) Number 2 clutch ring gear
(6) Number 2 sun gear
(8) Number 3 clutch ring gear
(9) Number 3 sun gear
(11) Number 4 clutch ring gear
(12) Number 4 sun gear
(13) Number 5 clutch
(14) Rotating Hub
(15) Number 4 carrier
(18) Input shaft
(21) Number 2 planetary gears
(22) Number 3 planetary gears
(24) Output shaft

When the transmission is in first speed forward, the number 5 clutch (13) and the number 2 clutch (4) are engaged. The number 2 clutch holds ring gear (5) stationary. The number 5 clutch connects rotating hub (14) to the number 4 carrier (15).

Input shaft (18) turns the number 2 sun gear (6). The number 2 sun gear turns planetary gears (21). Because ring gear (5) is held stationary by the number 2 clutch (4), planetary gears (21) move around the inside of the ring gear. The movement of planetary gears (21) causes number 2 carrier (3) and number 3 carrier (3) to turn in the same direction as input shaft (18).

As carrier (3) turns, planetary gears (22) turn ring gear (8) and sun gear (9). Sun gear (9) turns output shaft (24).

Ring gear (8) turns carrier (15). Carrier (15) is connected to rotating hub (14) by the engagement of number five clutch (13). This allows power to travel from carrier (15) to number 4 sun gear (12) and to number 4 ring gear (11). The power then travels through number 5 clutch to rotating hub (14). Sun gear (12) and rotating hub (14) are fastened to output shaft (24).

As a result, the torque to output shaft (24) is divided between number 3 sun gear (9), number 4 sun gear (12), and rotating hub (14). From the output shaft (24), power travels through the output transfer gears to the differentials.

Second Speed Forward



Illustration 3g01463703
Power Flow in First Speed Forward with the number 2 Clutch and the number 5 Clutch Engaged.
(3) Number 2 and Number 3 carrier
(4) Number 2 clutch
(5) Number 2 clutch ring gear
(6) Number 2 sun gear
(8) Number 3 clutch ring gear
(9) Number 3 sun gear
(10) Number 4 clutch
(11) Number 4 clutch ring gear
(12) Number 4 sun gear
(15) Number 4 carrier
(18) Input shaft
(21) Number 2 planetary gears
(22) Number 3 planetary gears
(23) Number 4 planetary gears
(24) Output shaft

When the transmission is in second speed forward, number 4 clutch (10) and number 2 clutch (4) are engaged. The number 2 clutch holds ring gear (5) for the number 2 clutch stationary. The number four clutch holds ring gear (11) for the number 4 clutch stationary. Input shaft (18) turns number two sun gear (6). Number two sun gear turns number two planetary gears (21).

Because ring gear (5) is held stationary by the number two clutch, planetary gears (21) move around the inside of the ring gear. The movement of planetary gears (21) causes number two carrier (3) and number three carrier (3) to turn in the same direction as input shaft (18). As the number two carrier and the number three carrier turn, number three planetary gears (22) turn. The number 2 planetary gears turn ring gear (8) for the number 3 clutch and number 3 sun gear (9). number three sun gear (9) turns output shaft (24). Ring gear (8) turns number four carrier (15).

Because ring gear (11) is held stationary by the number four clutch, planetary gears (23) move around the inside of the ring gear. The movement of planetary gears (23) causes number four sun gear (12) to turn. The number four sun gear turns output shaft (24).

As a result, the torque to output shaft (24) is divided between number three sun gear (9) and number four sun gear (12). From the output shaft, power travels through the output transfer gears to the differentials.

Third Speed Forward

Refer to Illustration 1 for the location of the components, as described below. Refer to Illustration 2 for a typical description of power flow in the forward direction.

When the transmission is in third speed forward, number 3 clutch (7) and number 2 clutch (4) are engaged. The number 2 clutch holds ring gear (5) for the number 2 clutch stationary. The number 3 clutch (7) holds ring gear (8) for the number 3 clutch stationary. Input shaft (18) turns number two sun gear (6). Number 2 sun gear turns number two planetary gears (21).

Because ring gear (5) is held stationary by the number 2 clutch, planetary gears (21) move around the inside of the ring gear. The movement of planetary gears (21) causes number 2 carrier (3) and number 3 carrier (3) to turn in the same direction as input shaft (18).

The movement of number 2 carrier (3) and number 3 carrier (3) causes number 3 planetary gears (22) to move around the inside of ring gear (8) because ring gear (8) is held stationary by the number 3 clutch. The movement of planetary gears (22) causes number 3 sun gear (9) to turn. The number 3 sun gear turns output shaft (24). From the output shaft, power travels through the output transfer gears to the differentials.

Third Speed Reverse



Illustration 4g01463712
Power Flow in Third Speed Reverse with the number 1 Clutch and the number 3 Clutch Engaged.
Transmission Components
(1) Coupling gear
(2) Number 1 clutch
(3) Number 2 and Number 3 carrier
(7) Number 3 clutch
(8) Number 3 clutch ring gear
(9) Number 3 sun gear
(16) Number 1 carrier
(17) Number 1 sun gear
(18) Input shaft
(19) Number 1 planetary gears
(20) Number 1 clutch ring gear
(22) Number 3 planetary gears
(24) Output shaft

When the transmission is in third speed reverse, number 3 clutch (7) and number 1 clutch (2) are engaged. The number 1 clutch holds coupling gear (1) stationary. The number 3 clutch holds ring gear (8) stationary. Input shaft (18) turns number 1 sun gear (17). Number 1 sun gear turns number 1 planetary gears (19). Number 1 carrier (16) is a direct mechanical connection with coupling gear (1).

Because coupling gear (1) is held stationary by the number 1 clutch, number 1 carrier (16) is also held stationary. The movement of number 1 planetary gear (19) causes ring gear (20) to turn in the opposite direction as input shaft (18). Ring gear (20) is a direct mechanical connection with number 2 carrier (3) and number 3 carrier (3).

The movement of number 2 carrier (3) and number 3 carrier (3) causes number 3 planetary gears (22) to move around the inside of the ring gear. This occurs because ring gear (8) is held stationary by the number 3 clutch. The movement of planetary gears (22) causes number 3 sun gear (9) to turn. The number 3 sun gear turns output shaft (24). From the output shaft, power travels through the output transfer gears to the differentials.

Second Speed Reverse

Refer to Illustration 1 for the location of the components, as described below. Refer to Illustration 4 for a typical description of power flow in the reverse direction.

When the transmission is in second speed reverse, number 4 clutch (10) and number 1 clutch (2) are engaged. The number 1 clutch holds coupling gear (1) stationary. The number 4 clutch holds ring gear (11) for the number 4 clutch stationary. Input shaft (18) turns number 1 sun gear (17). The number 1 sun gear turns number 1 planetary gears (19). Number 1 carrier (16) is a direct mechanical connection with coupling gear (1).

Because coupling gear (1) is held stationary by the number 1 clutch, number 1 carrier (16) is also held stationary. The movement of number 1 planetary gears (19) causes ring gear (20) to turn in the opposite direction as input shaft (18). Ring gear (20) is a direct mechanical connection with number 2 carrier (3) and number 3 carrier (3). As the number 2 carrier and the number 3 carrier turn, Number 3 planetary gears (22) turn. The number 3 planetary gears turn ring gear (8) for the number 3 clutch and number 3 sun gear (9). Number 3 sun gear (9) turns output shaft (24). Ring gear (8) turns number 4 carrier (15).

Because ring gear (11) is held stationary by the number 4 clutch, planetary gears (23) move around the inside of the ring gear. The movement of planetary gears (23) causes number 4 sun gear (12) to turn. The number 4 sun gear turns output shaft (24).

As a result, the torque to output shaft (24) is divided through number 3 sun gear (9) and number 4 sun gear (12). From the output shaft, power travels through the output transfer gears to the differentials.

First Speed Reverse

Refer to Illustration 1 for the location of the components, as described below. Refer to Illustration 4 for a typical description of power flow in the reverse direction.

When the transmission is in first speed reverse, number five clutch (13) and number one clutch (2) are engaged. The number 1 clutch holds coupling gear (1) stationary. The number five clutch connects rotating hub (14) and number four carrier (15).

Input shaft (18) turns number one sun gear (17). The number one sun gear turns planetary gears (19). Number one carrier (16) is a direct mechanical connection with coupling gear (1). Because coupling gear (1) is held stationary by the number one clutch, number one carrier (16) is also held stationary. The movement of number one planetary gears (19) causes ring gear (20) to turn in the opposite direction as input shaft (18). Ring gear (20) is a direct mechanical connection with number two carrier (3) and number three carrier (3).

As carrier (3) turns, planetary gears (22) turn ring gear (8) and sun gear (9). Sun gear (9) turns output shaft (24).

Ring gear (8) turns carrier (15). Carrier (15) is connected to rotating hub (14) by the engagement of the number 5 clutch (13). This allows power to travel from carrier (15) to sun gear (12) and to ring gear (11). The power then travels through the number 5 clutch (13) to rotating hub (14). Sun gear (12) and rotating hub (14) are fastened to output shaft (24).

As a result, the torque to output shaft (24) is divided between number 3 sun gear (9), number 4 sun gear (12), and rotating hub (14). From the output shaft, power travels through the output transfer gears to the differentials.

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