Caterpillar TA22-M4WD
Maintenance schedule, common problems & OEM parts breakdown
The Caterpillar TA22-M4WD is a Cat OEM Solutions product, not a complete machine: it is a direct-drive, 16Fx4R (16 forward, 4 reverse) electronic powershift transmission built to Cat's design and supplied to equipment manufacturers for factory installation. Buhler/Versatile installs it behind the Cummins QSX15, a six-cylinder, 15-liter turbocharged diesel, in its HHT-series 4WD row-crop tractors (435, 485, 535, and 575 models). A single control lever with a neutral-lock button and autoshift mode handles clutch-to-clutch shifting, backed by an electronic transmission control module. The unit has shipped across several build lots identified by serial prefix, including T4W, XAB, XAG, X4B, and X4G, representing updates to the same transmission rather than separate models.
Later build lots did not change the TA22-M4WD's basic gear layout, but Cat increased clutch capacity to raise torque handling in third, fourth, and fifth gear and loosened torque protection in the lower gears, along with smoother shift quality and a more consistent inching pedal. The oil filter location was also relocated for easier service. For the used-tractor and parts market, this matters because Buhler/Versatile 4WD owners depend on Cat OEM Solutions parts and rebuild support tied to the correct serial prefix rather than a marketed model change; matching clutch, seal, and filter kits to the right build lot is what keeps an older HHT-series tractor working and protects its resale value.
Below: full specifications, fluids & capacities, the factory service schedule, common service parts, verified fault codes, what owners discuss, attachment guidance, the complete assembly directory, and a serial-number reference. Complete parts lists with full OEM part numbers, exploded diagrams, quantities, and fitment data are available free in Heavy Parts AI.
Caterpillar TA22-M4WD specifications
Engine
| Product type | TA22-M4WD is a Cat OEM Solutions agricultural powershift transmission in the 4-wheel-drive output configuration, not a complete machine or engine. The figures below cover the transmission unit and the engines it is factory-paired behind. |
| Compatible engines | Fitted behind a 15-liter inline-six turbodiesel (Cummins QSX15/X15 family) in the large-frame 4WD and HHT tractor lines that offer this transmission, with gross engine ratings spanning roughly 435 to 620 hp (324 to 462 kW) depending on tractor model. No Cat-branded engine pairing is documented for this transmission in available literature. |
| Unconfirmed input rating | One isolated reference cites an input capacity near 440 kW (590 hp) with about 2,840 Nm (2,095 lb-ft) maximum torque, but this could not be corroborated by a second independent source, so treat it as unconfirmed for this exact configuration. |
Weights
| Transmission weight | Not published in available technical literature for this exact configuration. Whole-tractor operating weights exist for machines that use this transmission (roughly 19,000 kg / 42,000 lb for one large-frame 4WD model and up to about 26,700 kg / 58,850 lb for a tracked large-frame model), but those are complete-machine figures, not the weight of the transmission component itself. |
Dimensions
| Transport/installed dimensions | Not published. As an OEM driveline component rather than a complete vehicle, the TA22-M4WD is not assigned transport length, width, height, or ground-clearance figures by the manufacturer. |
Performance
| Speed configuration | 16 forward speeds and 4 reverse speeds (16Fx4R), direct-drive powershift design with a constant-mesh countershaft gear train and clutch packs distributed across five shafts, controlled by a transmission electronic control module. |
| Top travel speed | Up to about 40 km/h (25 mph) road speed on tractors equipped with this transmission, with 8 of the 16 forward ratios concentrated in the working speed range for field operations. |
| Shift control | Single-lever control with clutchless shifting between forward, neutral, and reverse; both manual-shift and auto-shift modes are supported, with auto-shift parameters operating in roughly the 1,650 to 2,100 engine rpm band on the updated calibration. |
| Torque capacity revision | A later production update increased clutch torque capacity versus the earlier calibration: about 3 percent more torque available in 3rd gear, 5 percent more in 4th gear, and full torque availability in 5th gear. An absolute torque rating specific to this configuration was not confirmed across independent sources. |
Service capacities (summary)
| Transmission oil/filter service | Transmission oil filter and breather serviced on a 250-hour interval per operator documentation. A specific transmission oil refill capacity for this configuration was not found in available sources — confirm with the equipment operator's manual or a Cat OEM Solutions representative before use. |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
TA22-M4WD fluids & capacities
| System | Capacity | Recommended fluid |
|---|---|---|
| Transmission / power train compartment (TA22-M4WD case oil) | Exact fill volume not documented in publicly available excerpts of the TA22-M4WD OMM/specifications manual; varies by configuration (XAB/XAG/T4W prefix build) — confirm against the serial-prefix-specific manual or Cat SIS before servicing. | Cat TDTO (Transmission/Drive Train Oil), meeting the Cat TO-4 performance spec, per the Cat Machine Fluids Recommendations guide referenced in this transmission's documentation set. SAE 30 grade TDTO for normal/warm ambient operation; SAE 10W TDTO for cold-weather starts. Cat TDTO-TMS (multi-viscosity, all-season) is the accepted single-fluid alternative to switching between SAE 30 and SAE 10W across seasons. |
| Chassis/driveline grease points (external U-joints, linkages, if equipped) | Spec only — no fill volume; lubricate per the grease-fitting interval in the OMM. | Cat multipurpose chassis grease, NLGI 2 (Cat MPGM / Advanced 3Moly Grease), or an equivalent NLGI 2 EP grease. |
Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.
Caterpillar TA22-M4WD maintenance schedule
| Service interval | Tasks |
|---|---|
| Every 10 h |
|
| Every 250 h |
|
| Every 500 h |
|
| Every 1,000 h |
|
| Every 2,000 h |
|
| Every 4,000 h |
|
Servicing the TA22-M4WD beyond the schedule
Predictive Maintenance & Fluid Analysis
Pull a TDTO oil sample every time the spin-on filter is changed and track wear metal and clutch material carryover between build lots. Watch the tractor's electronic instrument cluster for early transmission codes, especially low oil pressure and a plugged filter, before they escalate into a high-oil-temperature shutdown. Confirm level at the sight gauge daily against the correct hot or cold mark; a false low reading on cold oil is common, and topping off to the hot mark while cold will overfill the case.
Corrective & Common Repairs
Harsh engagement, delayed shifts, and an inconsistent inching pedal usually trace back to a clogged breather or a restricted spin-on filter starving the modulating valves, not a bad transmission control module. Inspect wiring and connectors at the solenoid pack before condemning electronics on a stored fault code. Clear codes only after the root cause is fixed, then confirm with a road test in both manual and autoshift mode. Repeat shift complaints call for a clutch calibration check via Cat ET before a valve body or clutch pack is replaced.
Overhaul & Rebuild Points
Because the TA22-M4WD is a direct-drive, five-shaft countershaft transmission rather than a torque-converter unit, overhaul work centers on the multi-disc clutch packs and the modulating valve body. Use Cat ET clutch calibration data over time to catch fill-time drift, the leading indicator of disc wear, before it shows up as a driveline shudder. Before ordering clutch, seal, or filter kits for a rebuild, confirm the unit's serial prefix (T4W, XAB, XAG, X4B, X4G), since the documented clutch-capacity upgrade changed component specs between lots.
Seasonal & Environment Servicing
Read the sight gauge against its cold mark before startup and its hot mark only once the transmission has reached operating temperature; filling to the hot mark on a cold unit overfills the case and can push oil out the breather. Ahead of a dusty harvest season, clean the transmission breather before the standard interval comes due to keep case pressure from building. Match TDTO viscosity to the season the way the factory matches engine oil grade for cold starting.
TA22-M4WD fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| F386 | High transmission oil temperature shutdown | Sump temperature exceeded the calibrated shutdown threshold, usually from overload, low oil level, or a plugged cooler | Idle down and let the unit cool, then check oil level and cooler airflow before restarting |
| F387 | Low transmission oil pressure warning | Low sump level, worn charge pump, or a pressure sensor reading below the calibrated minimum | Stop operation, check oil level and for visible leaks, then verify pressure with a gauge before returning to service |
| F388 | Transmission oil pressure sensor circuit shorted to ground | Chafed harness wire or failed sensor at the pressure transducer | Inspect the pressure sensor connector and wiring for shorts, then test or replace the sensor |
| F390 | Transmission oil temperature sensor open circuit or shorted to +battery | Broken wire, corroded pin, or failed temperature sensor at the sump | Check the temperature sensor connector and harness continuity, then replace the sensor if it fails to read correctly |
| F392 | Transmission filter plugged | Filter element loaded with debris or nearing its service interval | Replace the transmission filter and check for a bypass indication before returning to work |
| F703 | CAT data link not communicating | Broken or disconnected CAT data link wiring between the transmission controller and the display, or a controller power/ground fault | Check data link wiring and connectors between the transmission ECU and cab display, then rerun the self-test |
| F704 | J1939 data link not communicating | Break or short on the J1939 CAN backbone between the engine, transmission, and instrument controllers | Inspect J1939 harness, terminating resistors, and connectors, then verify network status with the dealer diagnostic tool |
| F705-F735 | Clutch solenoid circuit fault, reported per clutch (numbered roughly 1 through 9), each with short-to-ground, short-to-battery, or open-circuit variants | Failed shift solenoid coil, damaged harness pigtail inside the transmission case, or a bad connector at the solenoid valve body | Identify the specific clutch number and fault type from the display, then check that solenoid's wiring and coil resistance before condemning the valve body |
| F744-F746 | Transmission shift lever position sensor signal abnormal | Worn or misadjusted lever position sensor, or a loose linkage at the shift console | Check lever linkage adjustment and sensor connector, then recalibrate or replace the position sensor |
| F749 | Transmission overspeed | Output speed sensor reading exceeded the calibrated limit, often from downhill overrun or a wheel-speed mismatch | Reduce ground speed and downshift earlier on grades, then check output speed sensor readings if the fault repeats |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
TA22-M4WD attachments & work tools
Machine identity note
TA22-M4WD is a Cat OEM Solutions off-highway powershift transmission, not a work machine, so there are no bucket/fork-style work tools for it. "Attachments" here means the factory-offered driveline options and hardware groups used to configure the gearbox for its host tractor.
Power take-off (PTO) provision
The transmission is built either with a cover group without power take-off or with an added power take-off clutch group and matching cover. Adding PTO brings in an extra rotating clutch stage so the tractor can run a live PTO off the transmission.
Output yoke / driveline coupling
Front and rear power outputs terminate in separate yoke groups sized to bolt up to the tractor's front and rear driveshaft companion flanges, one yoke arrangement for each power-flow path out of the case.
Transfer gear / full-time 4WD drive
The M4WD build adds a transfer gear group that taps off power to the front axle for full-time four-wheel drive; two-wheel-drive TA22 builds omit this transfer stage, so front-drive hardware is specific to the 4WD variant.
Electronic clutch/shift control
Shift quality is managed by a 12V electronic modulating control valve that meters clutch pressure during ratio changes. The gearbox supports programmable autoshift and engine speed-matching logic through this same electronic control, shifted with a single control lever rather than a clutch pedal.
Mounting & engine interface
TA22 is a direct-drive, mid-mount powershift design (no torque converter) intended for engines of roughly 134 to 390 kW (180 to 525 hp) and communicates over J1939 CAN, which lets it pair with non-Cat engines. On Buhler/Versatile 4WD articulated tractors it is factory-matched to a Cummins diesel rather than a Cat engine.
Planetary gearset / speed range
Internal ratios come from a planetary case and parts group giving 16 forward and 4 reverse speeds (16Fx4R), shiftable on the go without a clutch pedal. Reported top road speed for this transmission in its tractor application is about 35 to 40 km/h (22 to 25 mph); treat the exact figure as varying by tractor model and final drive ratio.
Torque capacity / production revision
An updated production run of the TA22 increased clutch torque capacity versus the original release, with roughly 3 to 10 percent more torque handling added progressively through 3rd, 4th, and 5th gears and less restrictive torque protection in the lower gears. Confirm build level against the transmission's serial prefix for a given tractor before assuming which torque rating applies.
Typical host application / factory fit
This gearbox, in its M4WD full-time-4WD form, is the standard or optional factory transmission on large 4WD articulated agricultural tractors such as the Versatile/Buhler 500 and 550 series (optional on the smaller 435/485/535 range). It is not associated with any Cat quick-coupler or ground-engaging work-tool system.
All TA22-M4WD assemblies by section
Every catalogued assembly group for the Caterpillar TA22-M4WD. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Electrical And Starting System
161-9932 Sensor Gp-Pressure -Charge Pressure
| 10***03 | Kit; (Receptacle) (3-Pin) (Includes Receptacle As & Wedge) | 1 |
| 16***32 | Sensor Group-Pressure; -Transmission Oil | 1 |
| 3E***71 | Wedge; (Receptacle Lock) (3 Pin) | 1 |
Power Train
265-5694 Case & Parts Gp-Planetary
| 08***17 | Tack-Fastener | 2 |
| 10***05 | Elbow; (90 Degree) | 1 |
| 10***15 | Elbow Group | 1 |
265-5745 Clutch Gp-Power Take-Off
| 00***19 | Cone-Roller Bearing | 2 |
| 13***60 | Disc-Friction | 6 |
| 13***61 | Plate-Clutch | 6 |
246-8149 Clutch Gp-Transmission -Planetary
| 17***62 | Ring-Seal; (Exterior) | 1 |
| 17***63 | Ring-Seal; (Interior) | 1 |
| 17***65 | Gear-Ring; (92-Teeth) | 1 |
265-5697 Control Gp-Transmission Hyd -Hydraulic
| 10***02 | Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness) | 2 |
| 11***85 | Seal-O-Ring; (13.94mm Id) | 3 |
| 13***89 | Clip; (Ladder) | 13 |
265-5698 Cover Gp-Shipping
| 10***34 | Cover | 1 |
| 16***80 | Plug As. | 3 |
| 26***98 | Cover Group-Shipping | 1 |
265-5742 Cover Gp-Transmission -Without Power Take-Off
| 16***19 | Plug As | 1 |
| 26***42 | Cover Group-Transmission; -Without Power Take-Off | 1 |
| 26***43 | Cover | 1 |
265-5696 Drive Gp-Pump
| 17***90 | Cover | 1 |
| 17***81 | Gear; (36-Teeth) | 1 |
| 1F***71 | Bearing-Ball (Note D) | 2 |
265-5695 Gear Gp-Transfer
| 13***60 | Disc-Friction | 36 |
| 13***61 | Plate-Clutch | 36 |
| 16***00 | Plug | 4 |
293-5529 Transmission Ar -4-Wheel Drive
| 26***25 | Transmission Ar-Complete | 1 |
| 29***29 | Transmission Ar; -4-Wheel Drive | 1 |
265-5693 Transmission Ar
| 24***49 | Clutch Group-Transmission; -Planetary | 2 |
| 26***93 | Transmission Ar | 1 |
| 26***94 | Case & Parts Group-Planetary | 1 |
293-5528 Transmission Ar -4-Wheel Drive
| 26***24 | Transmission Ar-Complete | 1 |
| 29***28 | Transmission Ar; -4-Wheel Drive | 1 |
293-5530 Transmission Ar -4-Wheel Drive
| 26***28 | Transmission Ar-Complete | 1 |
| 29***30 | Transmission Ar; -4-Wheel Drive | 1 |
267-6624 Transmission Ar-Complete
| 26***93 | Transmission Ar | 1 |
| 26***97 | Control Group-Transmission Hydraulic; -Hydraulic | 1 |
| 26***98 | Cover Group-Shipping | 1 |
267-6628 Transmission Ar-Complete
| 26***93 | Transmission Ar | 1 |
| 26***97 | Control Group-Transmission Hydraulic; -Hydraulic | 1 |
| 26***98 | Cover Group-Shipping | 1 |
267-6625 Transmission Ar-Complete
| 26***93 | Transmission Ar | 1 |
| 26***97 | Control Group-Transmission Hydraulic; -Hydraulic | 1 |
| 26***98 | Cover Group-Shipping | 1 |
4t-5006 Valve Gp-Flow Control
| 2S***78 | Seal-O-Ring (Id=37.47mm) | 1 |
| 3D***24 | O-Ring - For Oil Drain & Level Plug (Items 3 & 7) | 1 |
| 4T***06 | Valve Group | 1 |
216-5343 Valve Gp-Modulating
| 16***08 | Washer; (13.03x25.4x2.38-mm Thk) | 1 |
| 16***24 | Nut-Self-Locking; (1/2-28-Thd) | 1 |
| 21***43 | Valve Group-Modulating | 1 |
198-1013 Valve Gp-Relief
| 11***50 | Cover | 1 |
| 17***66 | Body | 1 |
| 17***68 | Spool As | 1 |
267-6618 Yoke Gp
| 26***18 | Yoke Group | 1 |
| 27***82 | Yoke As | 1 |
| 3T***47 | Plug-Core | 1 |
267-6619 Yoke Gp
| 26***19 | Yoke Group | 1 |
| 27***94 | Yoke As | 1 |
| 3T***47 | Plug-Core | 1 |
267-6620 Yoke Gp
| 1T***31 | Guard | 1 |
| 26***41 | Spacer | 2 |
| 26***20 | Yoke Group | 1 |
267-6621 Yoke Gp
| 1T***31 | Guard | 1 |
| 22***48 | Yoke As | 1 |
| 26***41 | Spacer | 2 |
TA22-M4WD serial number reference
The identification plate for the TA22-M4WD is riveted directly to the transmission case (this is a bare OEM powertrain component, not a complete machine, so there is no operator's-compartment master plate). Read the three-letter prefix stamped on the plate followed by the sequential unit number, and match that prefix against the parts or service manual cover to confirm which manual set applies. The TA22-M4WD is a 16-forward/4-reverse powershift used behind Cummins QSX15 engines in large Buhler/Versatile 4WD row-crop tractors;
| Prefix | Identifies | Notes |
|---|---|---|
| T4W | TA22-M4WD AG Transmission, earliest documented build series | Earliest serial prefix documented for this transmission, dated to roughly the mid-2000s. Dry-sump unit weighs about 1750 kg (3860 lb). No mating-engine split is tied to this prefix in the OEM parts/service documentation; treat as a bare OEM powershift unit supplied to equipment builders. |
| XAB | TA22-M4WD AG Transmission, later build series | Appears in service documentation dated to around 2010. Same case and gearset family as the other prefixes; no engine-specific split documented. Confirm exact production window with a dealer. |
| XAG | TA22-M4WD AG Transmission, sibling series to XAB | Listed alongside XAB, also dated to around 2010. Appears to be a parallel or running-change build lot rather than a functional variant. Confirm with dealer. |
| X4B | TA22-M4WD AG Transmission, later build series | Appears in parts/service documentation dated to around 2011. No documented functional difference from the other prefixes beyond build-lot/date. Confirm with dealer. |
| X4G | TA22-M4WD AG Transmission, sibling series to X4B | Serial range begins 00001-up per parts documentation, dated to around 2011. Appears to be the most current documented build series for this transmission. Confirm with dealer. |
Frequently asked questions
What engine does the TA22-M4WD pair with?
The TA22-M4WD is factory-fit behind the Cummins QSX15, a six-cylinder, 15-liter turbocharged diesel used across the Buhler/Versatile HHT-series 4WD tractor line. Caterpillar does not build this engine; the TA22-M4WD is a Cat OEM Solutions transmission engineered to bolt up to it, not a Cat-engine machine.
How many speeds does the TA22-M4WD provide?
It is a 16Fx4R transmission: 16 forward speeds and 4 reverse speeds through a direct-drive countershaft gear train, shifted electronically through a single control lever with autoshift mode. Later build lots carry a documented clutch-capacity increase that raises torque handling in third through fifth gear, so confirm your unit's serial prefix when torque rating matters.
What replaced the TA22-M4WD?
No named successor is documented. Cat OEM Solutions transmissions are not retired and replaced with a marketed follow-on model the way complete machines are; the TA22-M4WD was instead revised in place across its T4W, XAB, XAG, X4B, and X4G build lots. If you need a direct parts match, verify your serial prefix with your dealer rather than searching for a successor model number.
What TA22-M4WD owners discuss
How does shifting actually feel on the TA22-M4WD, and is there a knack to it?
Why does reverse feel limited when the tractor is cold?
Is the left pedal a clutch pedal?
What fluid and clutch-pack habits do mechanics stress for long life?
Are there any known factory fixes or electronic quirks worth knowing about?
What should I check before buying a tractor fitted with a used TA22-M4WD?
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
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