D9T Track-Type Tractor Power Train – Undercarriage

Illustration 1 g01035627


(1) Rear Idler

(2) Rear Track Roller Frame

(3) Front Track Roller Frame

(4) Track

(5) Front Idler

(6) Major Bogie

(7) Minor Bogie

(8) Track Roller

The undercarriage consists of the following major components:

Track Roller Frames – The track roller frames consist of front track roller frame (3) and rear track roller frame (2) .

Pivot Shaft – The pivot shaft connects the roller frames to the machine main frame. Each roller frame can oscillate at the pivot shaft.

Equalizer Bar – The equalizer bar connects the two roller frames at the front of the machine. Oscillation of the roller frame is controlled by the equalizer bar.

Track Idlers – Front idler (5) is installed on front track roller frame (3). Rear idler (1) is installed on rear track roller frame (2) .

Major Bogies – Each major bogie (6) contains a cartridge pin. Minor bogies (7) pivot on these cartridge pins.

Minor Bogies – Each minor bogie (7) supports two track rollers (8) .

Track Rollers – Eight track rollers (8) on each side guide the tracks.

Tracks – Tracks (4) are sealed and lubricated for extended service life.

Track Roller Frame

Illustration 2 g01035711

Track Roller Frame

(1) Rear Track Roller Frame

(2) Pivot Shaft

(3) Access Port for Track Adjustment

(4) Recoil Oscillation Guide

(5) Front Track Roller Frame

Illustration 3 g01035712

Recoil Spring Assembly

(6) Valves

(7) Cylinder Assembly

(8) Piston

(9) Tube Assembly

(10) Retainer

(11) Spring

The track roller frame can be separated into two sections. Front track roller frame (5) has a large tube assembly that telescopes or slides into rear track roller frame (1). The recoil spring assembly is inside this tube.

A groove is machined in the outer diameter of the tube. Recoil oscillation guide (4) is installed in rear track roller frame (1). After installation, the oscillation guide is in alignment with the groove in the tube.

The oscillation guide prevents any rotation of the tube inside the rear section of the track roller frame. The guide allows the tube to move back and forth in the frame section during recoil.

Valves (6) are used for moving the front roller frame in order to adjust the track. When grease is pumped into the filler valve through port (3), piston (8) moves in a forward direction. This movement causes the front track roller frame to move out of the rear roller frame. The track tightens. Tension on the track is released by a relief valve.

Track Roller

Illustration 4 g01035956

Double Flange Track Roller

(1) Shaft

(2) Duo-Cone Seal

(3) Thrust Washer

The track rollers are fastened to the minor bogies. The track rollers are in contact with the inside surfaces of the track links. Flanges on the track rollers prevent movement of the track from side to side. The inside surfaces of the track links equally distribute the weight of the machine over the track.

Each track roller frame has eight track rollers. Four of the rollers are single flange rollers. Four of the rollers are double flange rollers.

Note: Some machines are equipped with only single flange rollers.

Rollers are arranged in the following sequence. Start at the front of the machine.

No. 1 Roller – Single flange

No. 2 Roller – Single flange

No. 3 Roller – Double flange

No. 4 Roller – Double flange

No. 5 Roller – Double flange

No. 6 Roller – Double flange

No. 7 Roller – Single flange

No. 8 Roller – Single flange

The track rollers have Duo-Cone seals (2) at both ends of shaft (1). Thrust washers (3) absorb the side load on the roller. The center of shaft (1) is an oil reservoir. This oil is used for lubrication of the bearing surfaces.

Track Idler

Illustration 5 g01035999

Track Idler

(1) Shaft

(2) Duo-Cone Seal

(3) Thrust Washer

Each track roller frame has a front idler and a rear idler.

The idler has Duo-Cone seals (2) at each end of shaft (1). Thrust washers (3) absorb the side load on the idler. The center of shaft (1) is an oil reservoir. This oil is used for lubrication of the bearing surfaces.


Illustration 6 g01035916

Track Assembly

(1) Track Link

(2) Bushing

(3) Hole

(4) Cavity

(5) Track Link

(6) Pin

(7) Track Link

(8) Track Link

(9) Thrust Ring

(10) Plug

(11) Stopper

(12) Seal Assembly

Each track link fits over the preceding track link. Track link (1) fits over track link (8). Track link (5) fits over track link (7). Each track link has a counterbore in the end that fits with the preceding track link. The connection of the track links make up the track assembly.

Seal assemblies (12) are installed in the counterbores of each track link. Each seal assembly has a load ring and a seal ring. The load ring pushes the seal ring against the end of bushing (2) and the link counterbore. The seal ring provides a positive seal between the bushing and the link counterbore.

Thrust rings (9) are installed on pin (6). The thrust ring provides a specific amount of compression to the seal assemblies. This controls the end play (free movement) of the track link joint. The arrangement of the seal assemblies and the thrust rings keeps the oil in the track link joint. The seals also keep foreign material out of the track link joint.

Pin (6) has cavity (4) which is almost the full length of the pin. Hole (3) is drilled radially in the pin near the center of the pin. Radial hole (3) allows oil to go to the surface between pin (6) and bushing (2). This oil lubricates the pin and the bushing. This oil also lubricates the lip of the seal ring. The lip of the seal ring must be kept lubricated in order to prevent wear.

Oil is kept in cavity (4) by stopper (11) and plug (10). Oil is installed in the track pin through a hole in the center of stopper (11). When the cavity is filled, plug (10) is installed in the stopper.

Equalizer Bar

Illustration 7 g01036006

Equalizer Bar

(1) Equalizer Bar Saddle

(2) Rubber Pads

(3) Track Roller Frames

(4) Equalizer Bar

(5) Pin

The track roller frames are connected together at the front by equalizer bar (4). Spherical bearings connect the equalizer bar to track roller frames (3) .

The equalizer bar pivots in the center around pin (5). Rubber pads (2) on the top of the equalizer bar control the amount of oscillation of the equalizer bar.

Pivot Shaft

Illustration 8 g01035738

Connection of Pivot Shaft to Track Roller Frame

(1) Bushing

(2) Bushing

(3) Pivot Shaft

(4) Track Roller Frame

The track roller frames are connected at the rear by pivot shaft (3). The pivot shaft is also connected to the main frame of the machine.

The track roller frames oscillate about the pivot shaft on bearings (1) and (2) .

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