Caterpillar BR378
Maintenance schedule, common problems & OEM parts breakdown
The Cat BR378 is a hydraulically driven rotary brushcutter, a work tool rather than a self-powered machine, built for Cat skid steer, compact track, and multi-terrain loaders. It carries no onboard engine, fuel tank, or cooling system; a 196 cm³/rev hydraulic drive motor mounted on the deck feeds a sealed, heat-treated gearbox that spins the blade carrier, drawing roughly 76-130 L/min (20-34 gpm) at 150-280 bar (2,176-4,065 psi) from the carrier's high-flow or high-flow XPS auxiliary circuit. At 535 kg (1,180 lb) it is the heaviest model in Cat's brushcutter range, with a 1981 mm (78 in) cutting width, about 2032 mm (80 in) overall width, and a rated cutting capacity up to 76 mm (3 in) diameter material. It mounts on the standard Cat universal quick-attach plate and is listed compatible with the 246D, 262D, 272D, 272D XHP, 277D, 279D, 287D, 289D, 297D, 297D XHP, 299D, 299D XHP carriers and their D2-series equivalents (272D2, 297D2, 299D2 and XHP variants), with a conversion kit called out for some D-series machines to reach the required high-flow XPS circuit. Only one factory serial prefix, RDN, is documented for the line.
The BR378 sits at the top of Cat's brushcutter sizing ladder, which runs from the BR160 (1524 mm/60 in cut, roughly 431 kg/950 lb) through the BR166 (1676 mm/66 in), BR172 and BR272 (1829 mm/72 in), up to the BR378 at 1981 mm (78 in) and 535 kg (1,180 lb). Each step up adds cutting width, weight, and hydraulic demand, and the two largest models, BR272 and BR378, are the only ones built for high-flow/XPS circuits while the three smaller models run on standard flow; no separate generation or mid-life redesign is documented for the BR378 itself, just the one RDN-prefixed build throughout production. In the used and parts market it matters as the widest, highest-capacity brushcutter Cat offers for compact loaders, so it's shopped specifically by owners who already have a high-flow-equipped carrier and want maximum cutting width from it. Because it has no engine or ECU, its condition and resale value turn almost entirely on gearbox health, coupler integrity, and blade-carrier balance rather than hours on a powerplant.
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 BR378 specifications
Engine
| Power source | No onboard engine. BR378 is a hydraulically driven work tool powered by the carrier machine's hydraulic system (skid steer, multi terrain, or compact track loader). |
| Drive motor displacement | 196 cm³/rev (12.0 in³/rev) |
| Drive shaft torque | 297-554 N·m (219-409 lb-ft) |
| Emissions tier | Not applicable - no combustion engine on the attachment |
Weights
| Unit weight | 535 kg (1,180 lb) |
Dimensions
| Overall width | 2032 mm (80 in) |
| Overall length | 2311 mm (91 in) |
| Overall height | 531 mm (21 in) |
| Cutting width | 1981 mm (78 in) |
| Maximum cutting diameter (material) | 76 mm (3 in) |
Performance
| Hydraulic flow requirement | 76-130 L/min (20-34 gpm) - requires high flow or high flow XPS option on the carrier machine; some D Series XHP machines need a conversion kit |
| Hydraulic pressure requirement | 150-280 bar (2,176-4,065 psi) |
| Blade tip speed range | 4,176-6,032 m/min (13,700-19,790 fpm), varies with hydraulic flow supplied |
| Carrier compatibility | 246D, 262D, 272D, 272D XHP, 277D, 279D, 287D, 289D, 297D, 297D XHP, 299D, 299D XHP, 272D2, 272D2 XHP, 297D2, 297D2 XHP, 299D2, 299D2 XHP |
Service capacities (summary)
| Fuel tank | Not applicable - work tool has no fuel system |
| Hydraulic system | Supplied by carrier machine; no dedicated reservoir on the attachment |
| Engine oil | Not applicable - no engine |
| Cooling system | Not applicable - no engine |
| Gearbox | Sealed gearbox with machined, heat-treated gears; no published service fill capacity |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
BR378 fluids & capacities
| System | Capacity | Recommended fluid |
|---|---|---|
| Gearbox (sealed speed-reducer between the hydraulic drive motor and blade carrier) | Exact fill quantity is not documented. The gearbox is a small sealed case checked at a level plug rather than a dipstick, and level is checked every 50 service hours or monthly, with an oil change every 500 service hours or 1 year. | Cat brush-cutter gearboxes of this family call for an SAE 80W-90, API GL-5 multigrade gear lubricant (Cat GO gear oil or an equivalent 80W-90/85W-140 multigrade gear lube). No separate cold-weather/hot-weather viscosity split is documented for this work tool. |
| Grease points (blade-carrier bearing, frame pivots, quick-coupler linkage) | Not a fill-capacity item. These are zerk-fitting grease points serviced per the lubrication schedule rather than a chart quantity; daily to weekly greasing is typical for the blade-carrier bearing under normal duty. | Standard Cat Multipurpose Grease (Cat MPGM), an NLGI multipurpose EP grease, is the general-duty recommendation for this class of Cat work tool. No climate-graded (arctic/tropical) grease variant is documented specifically for the BR378. |
Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.
Caterpillar BR378 maintenance schedule
| Service interval | Tasks |
|---|---|
| Every 50 h |
|
| Every 250 h |
|
| Every 500 h |
|
| Every 1,000 h |
|
| Every 2,000 h |
|
| Every 3,000 h |
|
Servicing the BR378 beyond the schedule
Predictive maintenance & fluid analysis
The BR378's only lubricated driveline component is its sealed gearbox between the hydraulic drive motor and blade carrier. Pull an oil sample at each 250-hour interval and watch for metal fines or discoloration that flag gear or bearing wear before it reaches the input seal. Track the carrier's flow-control setting against the tool's 76-130 L/min rated band; running full detent flow on an oversized high-flow carrier is the leading precursor to coupler and gearbox damage on this model.
Corrective & common repairs
The BR378's signature failure is a sheared bolt in the coupler joining the hydraulic drive motor to the gearbox: the motor spins freely but no drive reaches the blades. It traces to running full detent flow on a high-flow carrier rated above the tool's 76-130 L/min band. Repair means replacing the sheared bolt, checking coupler and gearbox alignment, and resetting the carrier's flow control to roughly 70 percent of max instead of leaving it wide open.
Overhaul & rebuild points
Overhaul on the BR378 centers on two assemblies: the sealed gearbox and the blade carrier. Rebuild the gearbox when oil sampling shows metal, the input seal weeps persistently, or gear noise develops, replacing gears, bearings, and seals together. Rebuild or replace the blade carrier when its bearing develops play or the carrier itself loses balance from stump and rock strikes, since an unbalanced carrier feeds vibration straight back through the coupler and gearbox.
Seasonal & environment servicing
Ground conditions drive service on the BR378 more than the calendar. Rocky or stump-heavy sites wear blade edges, mounting hardware, and skid shoes fastest, so check skid shoes and the deck underside each shift and flip or replace shoes before the deck drags and gouges. Ahead of heavy-clearing seasons, regrease the blade-carrier bearing, frame pivots, and coupler linkage, confirm deflector chains and the stump jumper are intact, and recheck gearbox oil level and seal condition.
BR378 attachments & work tools
Product identity
The BR378 is itself a Cat rotary brushcutter work tool for skid steer loaders, compact track loaders and multi terrain loaders, not a carrier machine. It is the widest model in the Cat brushcutter lineup, offering a 1981 mm (78 in) cutting width and roughly 2032 mm (80 in) overall width.
Family / size class comparison
The Cat brushcutter range runs BR160 at 1524 mm (60 in), BR166 at 1676 mm (66 in), BR172 and BR272 at 1829 mm (72 in), up to the BR378 at 1981 mm (78 in) cut. Weight scales with size, from about 431 kg (950 lb) on the BR160 to about 535 kg (1180 lb) on the BR378; all models share a 76 mm (3 in) maximum stem/branch cutting diameter.
Mounting / coupler system
BR378 uses the standard Cat universal quick-attach interface for skid steer and multi terrain loaders, mating to the carrier's integrated mechanical quick coupler and hydraulic quick couplers for fast tool changes.
Hydraulic requirement
BR378 is sized for high-flow auxiliary hydraulics, with an optimal flow window of about 76-130 L/min (20-34 gpm) and operating pressure around 150-280 bar (2176-4065 psi). It is matched specifically to a carrier's high-flow or high-flow XPS circuit; smaller family members (BR160/BR166/BR172) run on lower standard-flow ranges of roughly 57-80 L/min (15-21 gpm), so flow rating is not interchangeable across the family.
Carrier compatibility / conversion kit
Listed compatible carriers include Cat 246D, 262D, 272D and 272D XHP, 277D, 279D, 287D, 289D, 297D and 297D XHP, 299D and 299D XHP, plus D2-series equivalents (272D2/XHP, 297D2/XHP, 299D2/XHP). A conversion kit is called out as needed to run the BR378 on D-series machines to match the required high-flow XPS circuit; verify the exact kit and flow option with the dealer for a given serial range.
Guarding / debris containment
Standard guarding consists of front and rear deflector chains (galvanized coil-chain curtains) around the cutting deck to contain thrown debris during operation.
Ground/stump protection
BR378 includes a stump jumper on the deck to help the housing ride up and over stumps and obstacles instead of catching on them, standard across the size class.
Blade / rotor design
The cutting rotor uses high-strength blades intended for aggressive cutting action and mulching of overgrowth, with a blade carrier described as fully balanced to reduce vibration transmitted to the carrier machine. Tip speed varies with flow supplied, roughly 4176-6032 m/min (13,700-19,790 fpm) across the optimal flow range.
Typical duty / configuration notes
BR378 and its family are marketed for clearing overgrowth on highway medians and utility easements and for initial land-clearing ahead of housing, parks and recreational-area development; no separate factory forestry/mulching guarding package beyond the standard deflector chains is documented for this model.
All BR378 assemblies by section
Every catalogued assembly group for the Caterpillar BR378. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Frame And Body
264-9510 Frame Gp-Brush Cutter -66-In
| 16***20 | Link-Chain | 2 |
| 26***10 | Frame Group-Brush Cutter; -66-In | 1 |
| 26***11 | Frame As | 1 |
264-9410 Frame Gp-Brush Cutter -60-In
| 16***20 | Link-Chain | 2 |
| 26***10 | Frame Group-Brush Cutter; -60-In | 1 |
| 26***11 | Frame As | 1 |
264-9010 Frame Gp-Brush Cutter -78-In
| 16***20 | Link-Chain | 2 |
| 26***10 | Frame Group-Brush Cutter; -78-In | 1 |
| 26***11 | Frame As | 1 |
264-9310 Frame Gp-Brush Cutter -72-In, High Flow
| 16***20 | Link-Chain | 2 |
| 26***10 | Frame Group-Brush Cutter; -72-In, High Flow | 1 |
| 26***11 | Frame As | 1 |
Hydraulic System
264-9540 Lines Gp-Connecting -66-In
| 14***22 | Adapter; (-10orb/-12orfs) | 4 |
| 15***94 | Coupler As-Quick Disconnect; (Female)(Quick Disconnect) | 1 |
| 15***95 | Fitting As; (Quick Disconnect, Male) | 1 |
264-9240 Lines Gp-Connecting -72-In, High Flow
| 14***48 | Fitting As; (Quick Disconnect, Male) | 1 |
| 14***49 | Fitting As; (Quick Disconnect, Female) | 1 |
| 14***22 | Adapter; (-10orb/-12orfs) | 2 |
264-9040 Lines Gp-Connecting -78-In
| 14***48 | Fitting As; (Quick Disconnect, Male) | 1 |
| 14***49 | Fitting As; (Quick Disconnect, Female) | 1 |
| 14***27 | Connector Group | 4 |
264-9033 Manifold Gp-Control
| 14***88 | Kit-Seal; (Ride Control, Switch) | 1 |
| 26***33 | Manifold Group-Control | 1 |
| 26***34 | Valve-Relief | 1 |
Service Equipment And Supplies
264-9098 Plate & Film Gp -78-In
| 12***56 | Film; (Warning) (No Step) (On Top Of Hood Behind Cab On Each Side) (On Each Fender Flare) | 3 |
| 15***36 | Film-Warning; (Read Operation Manual) | 1 |
| 15***41 | Film-Warning; (Cutter Hazard, Stay Back) | 1 |
264-9598 Plate & Film Gp -66-In
| 12***56 | Film; (Warning) (No Step) (On Top Of Hood Behind Cab On Each Side) (On Each Fender Flare) | 3 |
| 15***36 | Film-Warning; (Read Operation Manual) | 1 |
| 15***41 | Film-Warning; (Cutter Hazard, Stay Back) | 1 |
264-9498 Plate & Film Gp -60-In
| 12***56 | Film; (Warning) (No Step) (On Top Of Hood Behind Cab On Each Side) (On Each Fender Flare) | 3 |
| 15***36 | Film-Warning; (Read Operation Manual) | 1 |
| 15***41 | Film-Warning; (Cutter Hazard, Stay Back) | 1 |
264-9398 Plate & Film Gp -72-In
| 12***56 | Film; (Warning) (No Step) (On Top Of Hood Behind Cab On Each Side) (On Each Fender Flare) | 3 |
| 15***36 | Film-Warning; (Read Operation Manual) | 1 |
| 15***41 | Film-Warning; (Cutter Hazard, Stay Back) | 1 |
264-9298 Plate & Film Gp -72-In, High Flow
| 12***56 | Film; (Warning) (No Step) (On Top Of Hood Behind Cab On Each Side) (On Each Fender Flare) | 3 |
| 15***36 | Film-Warning; (Read Operation Manual) | 1 |
| 15***41 | Film-Warning; (Cutter Hazard, Stay Back) | 1 |
Work Tool Arrangement
264-9600 Brush Cutter Ar -66-In
| 26***10 | Frame Group-Brush Cutter; -66-In | 1 |
| 26***40 | Lines Group-Connecting; -66-In | 1 |
| 26***50 | Drive Group-Brush Cutter | 1 |
264-9100 Brush Cutter Ar -78-In, Xps
| 26***10 | Frame Group-Brush Cutter; -78-In | 1 |
| 26***40 | Lines Group-Connecting; -78-In | 1 |
| 26***50 | Drive Group-Brush Cutter; -78-In | 1 |
264-9500 Brush Cutter Ar -60-In
| 26***10 | Frame Group-Brush Cutter; -60-In | 1 |
| 26***50 | Drive Group-Brush Cutter; -60-In | 1 |
| 26***98 | Plate & Film Group; -60-In | 1 |
264-9400 Brush Cutter Ar -72-In
| 26***10 | Frame Group-Brush Cutter; -72-In, High Flow | 1 |
| 26***50 | Drive Group-Brush Cutter; -72-In, High Flow | 1 |
| 26***98 | Plate & Film Group; -72-In | 1 |
264-9300 Brush Cutter Ar -72-In, High Flow
| 26***40 | Lines Group-Connecting; -72-In, High Flow | 1 |
| 26***98 | Plate & Film Group; -72-In, High Flow | 1 |
| 26***00 | Brush Cutter Ar; -72-In, High Flow | 1 |
Work Tools
264-9450 Drive Gp-Brush Cutter -60-In
| 26***50 | Drive Group-Brush Cutter; -60-In | 1 |
| 26***51 | Blade | 1 |
| 26***52 | Pin | 2 |
264-9550 Drive Gp-Brush Cutter
| 26***50 | Drive Group-Brush Cutter | 1 |
| 26***51 | Blade Set | 1 |
| 26***54 | Coupling | 1 |
264-9350 Drive Gp-Brush Cutter -72-In, High Flow
| 26***50 | Drive Group-Brush Cutter; -72-In, High Flow | 1 |
| 26***51 | Blade; (Includes 2-Blades) | 1 |
| 26***52 | Pin | 2 |
264-9050 Drive Gp-Brush Cutter -78-In
| 17***95 | Bolt-Socket Head; (3/8-16x3.5-In) | 8 |
| 26***33 | Manifold Group-Control | 1 |
| 26***50 | Drive Group-Brush Cutter; -78-In | 1 |
264-9560 Gearbox Gp -Speed Increaser
| 26***60 | Gearbox Group; -Speed Increaser | 1 |
| 26***61 | Seal-Shaft | 1 |
| 26***62 | Seal-Shaft | 1 |
BR378 serial number reference
The BR378 serial/PIN tag is riveted to the brush cutter frame near the gearbox housing or the quick-attach mounting plate, not on an engine (the tool has none). Read it as a 3-letter prefix (RDN) followed by a sequential unit number; there is no model-year-coded segment like on self-powered Cat machines.
| Prefix | Identifies | Notes |
|---|---|---|
| RDN | BR378 HD brush cutter, 78 in (198 cm) cut width, high-flow (XPS) skid-steer quick-attach with stump jumper | Only factory serial prefix documented for the BR378 line, running as RDN1-Up. BR378 is a hydraulically driven skid-steer work tool with no engine of its own; it runs off the host machine's hydraulic circuit, so there is no separate engine fitment to report. It is matched to the machine's high-flow (XPS) auxiliary hydraulic circuit, not the standard-flow circuit used by the smaller BR160/BR166/BR172 brush cutters in the same family - flow spec runs roughly 76-130 L/min (20-34 gpm) at 150-280 bar (2,176-4,065 psi), so confirm host-machine flow compatibility before ordering. No second-generation or alternate prefix turned up for this model. Plant/region of manufacture not documented in available listings - confirm with dealer if needed. |
Frequently asked questions
Does the BR378 have an engine?
No. The BR378 has no onboard engine, fuel tank, or cooling system. It's a hydraulic attachment driven entirely by the carrier machine's auxiliary hydraulic circuit, through a 196 cm³/rev hydraulic drive motor feeding a sealed gearbox. It needs about 76-130 L/min (20-34 gpm) at 150-280 bar (2,176-4,065 psi) from a carrier fitted with the high-flow or high-flow XPS hydraulic option.
What's the BR378's operating weight?
About 535 kg (1,180 lb), the heaviest model in Cat's brushcutter lineup. That's up from roughly 431 kg (950 lb) on the smallest BR160 in the same family, with weight scaling up alongside cutting width across the range.
What replaced the BR378?
Nothing documented. The BR378 remains Cat's current top-end brushcutter, the widest in the lineup at 1981 mm (78 in) cut, sitting above the BR272 and BR172 (72 in), BR166 (66 in), and BR160 (60 in) rather than being superseded by a later model.
What BR378 owners discuss
What hydraulic flow and pressure does the BR378 actually need from the carrier?
What's the failure mode owners report when the blades stop turning but the hydraulic motor still spins?
Does bolting on the quick-attach plate get this tool running, or is there more to hook up?
What does the gearbox need on a maintenance schedule?
What wear should owners expect on the blades and blade carrier?
What about the deck and skid shoes, do they wear differently from the blades?
What should a buyer check before purchasing a used BR378?
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
Need a specific BR378 part?
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