News & Insights
FAST (Shaanxi Fast Gear Co., Ltd.) is the dominant transmission manufacturer for Chinese heavy trucks, supplying gearboxes to Sinotruk, Shacman, FAW, and most other major OEMs as standard fitment. When a fleet operator, parts importer, or workshop manager needs a replacement gearbox or transmission parts, the model number is the essential starting point — and FAST's numbering system is logical once you understand the structure.
This guide covers the three main series: 9JS, 12JS, and 16JS. For each, we explain the gear count, torque capacity, typical truck applications, and the specific model variants you are most likely to encounter in the field.
Before comparing series, the model number structure is worth understanding — it eliminates guesswork when cross-referencing a gearbox from a vehicle data plate or a parts invoice.
Take 12JS200T as an example:
12 — Number of forward gears
JS — Synchronized gearbox (the standard designation across all series)
200 — Maximum input torque, expressed in units of 10 N·m. So 200 = 2,000 N·m
T — Variant suffix indicating an enhanced or specific engineering configuration
Additional characters you will encounter:
D — Double countershaft design (e.g., 12JSD), used for heavier torque loads
X — Extended or cross-country variant (e.g., 12JSDX)
A — Indicates a specific generation update
TA, XA — Combinations of the above
When you see these suffixes on a parts order or a vehicle specification sheet, they indicate a distinct gearbox configuration — not just a minor revision. Sourcing a 12JS200 when the vehicle runs a 12JSD200 will result in a non-fit.
The 9JS is FAST's 9-speed synchronized gearbox, positioned below the 12JS in terms of torque capacity and application weight. It is a direct-drive unit designed for trucks in the 220 HP–310 HP range where the full 12-speed range is not required and the lower unit cost and simpler shift pattern offer operational advantages.
In export markets, the 9JS is common on FAW J6 configurations, Dongfeng Tianlong medium-spec versions, and Shacman F3000 trucks built for lighter-duty regional haulage. It is less frequently seen on dedicated long-haul tractors, where the 12JS has become the default.
| Model | Forward Gears | Max Input Torque | Typical Power Range | Primary Application |
|---|---|---|---|---|
| 9JS119 | 9 | 1,190 N·m | 220–270 HP | Medium-heavy trucks, municipal |
| 9JS135 | 9 | 1,350 N·m | 250–290 HP | Regional haulage, construction |
| 9JS135A | 9 | 1,350 N·m | 250–290 HP | Updated variant of 9JS135 |
| 9JS150 | 9 | 1,500 N·m | 270–310 HP | Heavier regional applications |
| 9JS180T | 9 | 1,800 N·m | 290–340 HP | Upper range, tractor applications |
The 9JS suits operations where routes are shorter, load weights are moderate, and a simpler gear range reduces driver fatigue and training requirements. In urban distribution, municipal, and construction support applications, the 9-speed pattern is adequate and the lower unit cost is a genuine advantage.
It is not the correct specification for sustained long-haul at maximum GVW. At the upper end of payload and distance, the limited gear spread of the 9-speed configuration forces the driver to operate outside the engine's optimal torque band more frequently, increasing fuel consumption and engine wear relative to a 12-speed unit.
9JS gearboxes are typically paired with Weichai WD615 or WP10 engines in the 266–336 HP range on FAW and Shacman platforms. The bellhousing interface and PTO provisions differ from the 12JS — always confirm the full model number and bellhousing specification when ordering a replacement assembly.
The 12JS is the most widely deployed FAST gearbox series in the Chinese heavy truck industry and in export markets. It is the standard fitment on HOWO A7, HOWO T5G, Shacman X3000, and FAW J6P trucks configured for long-haul tractor and tipper applications. If your operation runs Chinese heavy trucks built after 2010, the majority of the fleet is almost certainly running a 12JS variant.
The 12-speed range gives drivers the gear spread to keep the engine in its power band across a wide range of gradients and load conditions — which is why it became the default for variable-terrain, mixed-load operations that characterize the bulk of Chinese truck export markets in Africa, the Middle East, and Southeast Asia.
| Model | Forward Gears | Max Input Torque | Typical Power Range | Primary Application |
|---|---|---|---|---|
| 12JS160T | 12 | 1,600 N·m | 266–310 HP | Standard tractor, lighter spec |
| 12JS180T | 12 | 1,800 N·m | 310–336 HP | Standard long-haul tractor |
| 12JS200T | 12 | 2,000 N·m | 336–375 HP | Most common variant — HOWO, Shacman |
| 12JS240T | 12 | 2,400 N·m | 375–420 HP | Higher-power tractor and tipper |
| 12JS260T | 12 | 2,600 N·m | 400–430 HP | High-torque long-haul |
| 12JSD200T | 12 | 2,000 N·m | 336–380 HP | Double countershaft — heavier loads |
| 12JSDX200 | 12 | 2,000 N·m | 336–380 HP | Extended cross-country variant |
The 12JS200T deserves particular attention because it is by far the most common variant in the field. It is the standard transmission on the HOWO A7 6×4 tractor truck with WD615 or WP10 336 HP engine — which represents a very large proportion of the Chinese heavy trucks operating across Africa and the Middle East.
Its 2,000 N·m input torque rating matches the torque output of WD615.46 and WP10.336 engines at operating load, making it a designed pairing rather than a general-purpose fit. For fleet operators sourcing replacement gearboxes, the 12JS200T is the unit to verify against the vehicle data plate before ordering.
Key 12JS200T data points for procurement reference:
Input shaft spline: 50-tooth, standard Weichai/WD615/WP10 interface
PTO provision: single PTO port, right side
Gear ratios (1st through 12th): 14.28 / 10.59 / 7.81 / 5.79 / 4.26 / 3.16 / 2.37 / 1.76 / 1.29 / 0.96 / 0.72 / 0.59
Reverse: 12.92
Oil capacity: approximately 11 litres
The 12JSD and 12JSDX variants use a twin countershaft design that distributes load across two gear meshes instead of one. This increases torque capacity and durability under sustained heavy loading, which is why these variants are specified on tipper trucks operating in mining and construction environments where sustained low-gear operation under load is the norm rather than the exception.
The double countershaft design also makes these units heavier and more complex to rebuild. Parts interchangeability with the standard single-countershaft 12JS is limited — input and output shafts, gear sets, and bearings are not cross-compatible in most cases. This is one of the most common sourcing errors encountered in the field: ordering 12JS parts for a vehicle running a 12JSD.
The 16JS series is FAST's premium transmission range, designed for high-horsepower tractors operating at maximum GVW over long distances. It is specified on trucks running WP12, WP13, or equivalent engines in the 420 HP–550 HP range — including high-specification HOWO T7H, Shacman X5000, and FAW J7 configurations.
The 16-speed range provides finer gear steps across the entire power band, allowing the engine to operate closer to its peak torque at all speeds and gradients. For long-haul operators calculating fuel cost per kilometre at scale, this granularity translates into measurable efficiency gains over a 12-speed unit at the same power level.
| Model | Forward Gears | Max Input Torque | Typical Power Range | Primary Application |
|---|---|---|---|---|
| 16JS200 | 16 | 2,000 N·m | 375–420 HP | Upper-spec long-haul |
| 16JS221 | 16 | 2,210 N·m | 400–440 HP | High-power tractor standard |
| 16JS260 | 16 | 2,600 N·m | 430–480 HP | Heavy long-haul, high GVW |
| 16JS300 | 16 | 3,000 N·m | 480–550 HP | Top-spec, maximum-load applications |
The 16JS is the correct specification for:
Long-haul tractor-trailer operations at maximum GVW, particularly on routes with significant elevation change. The additional gear steps allow the driver to maintain engine speed in the power band on sustained mountain grades without the lugging or over-revving that characterises a 12-speed unit in the same conditions.
High-value, time-sensitive freight where fuel efficiency and reduced driveline stress contribute to lower total operating cost per trip. The 16JS capital cost premium over a 12JS is typically recovered within 18–24 months on high-utilisation routes.
The 16JS is generally not specified for construction, tipper, or off-road applications, where the JSD double-countershaft 12JS variants offer better durability under the repeated shock loads of dump cycles and uneven terrain. The 16-speed unit's refined gear steps offer diminishing benefit in stop-start or off-road operation.
The 16JS has fewer units in the field than the 12JS, which means parts availability requires more planning. Synchroniser rings, input shaft assemblies, and gear sets for 16JS units are held by fewer distributors and at lower stock levels than equivalent 12JS parts. For fleet operators transitioning to 16JS-equipped trucks, establishing a supply relationship with a distributor that holds 16JS parts inventory before the fleet goes operational is a practical risk management step.
| Criteria | 9JS | 12JS | 16JS |
|---|---|---|---|
| Forward gears | 9 | 12 | 16 |
| Torque range | 1,190–1,800 N·m | 1,600–2,600 N·m | 2,000–3,000 N·m |
| Engine power range | 220–310 HP | 266–430 HP | 375–550 HP |
| Typical truck | FAW J6 medium, Shacman F3000 | HOWO A7/T5G, Shacman X3000, FAW J6P | HOWO T7H, Shacman X5000, FAW J7 |
| Best for | Regional, urban, construction support | Mixed-use, standard long-haul | High-GVW long-haul, premium spec |
| Parts availability | Good | Excellent | Moderate |
| Serviceability | Straightforward | Straightforward | Requires specialist knowledge |
The vehicle data plate and the gearbox data plate are the definitive references — not the truck model name alone, because the same truck model is frequently produced across multiple transmission specifications depending on the build year, horsepower variant, and export market configuration.
The gearbox data plate is typically located on the side of the gearbox housing and will show the full model number including suffix characters. When contacting us for a replacement assembly or individual parts, providing this number avoids the compatibility errors that are the most common cause of procurement delays.
If the data plate is illegible or missing, the engine model and horsepower combined with the truck model and build year will allow us to confirm the correct gearbox specification in most cases.
We are an authorized distributor for FAST (Shaanxi Fast Gear) and hold dedicated warehouse stock covering assembly units and individual parts across the 9JS, 12JS, and 16JS series. Our FAST warehouse carries input shafts, output shafts, intermediate shafts, synchroniser rings, gear sets, PTO units, and complete assembly units for the most common models.
For the 12JS200T and 12JS240T in particular, we maintain real-time inventory to support fast dispatch requirements.
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To request a quote, send us your gearbox model number, required quantity, and destination port. We confirm availability, unit price, and lead time within 24 hours on business days.
