Caterpillar BU115
Maintenance schedule, common problems & OEM parts breakdown
The Cat BU115 is a hydraulically-driven utility broom attachment built for skid steer loaders, compact track loaders, multi terrain loaders, and compact wheel loaders. It has no engine, fuel tank, or onboard hydraulic pump of its own. It mounts through a standard Cat quick coupler and draws hydraulic flow from the host carrier's auxiliary circuit through a two-line quick-attach hookup, driving a direct-drive, bi-directional gerotor motor housed in a bracket that adjusts to compensate for bristle wear. At 422 kg (930 lb) unit weight, 1810 mm (71 in) overall width, and a 660 mm (26 in) brush diameter, it sits in the compact end of the broom lineup. It ships standard with a polypropylene/wire convoluted bristle core, with optional all-polypropylene or all-steel wire cores for turf, snow, or compacted-material work, plus an optional water sprinkler kit for dust suppression.
In the field, the BU115 clears dirt, gravel, cold-planer millings, and general debris from streets, lots, sidewalks, and factory floors ahead of paving, milling, and general construction crews, and sees regular use on rental and municipal fleets. Because it carries no engine, filters, or fluid reservoir of its own, its service story is short: bristle wear, bearing grease, motor case condition, and coupler/hose fit are the whole picture. That simplicity is exactly why it holds steady demand in the used and parts market today — buyers can judge condition quickly without an hour-meter or oil-analysis history, and worn units are cheap to bring back into service with a bristle core, bearing, or motor exchange rather than a major rebuild.
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 BU115 specifications
Engine
| Power source | No onboard engine. Hydraulically driven work tool powered by the carrier machine's auxiliary hydraulic circuit. |
| Drive motor | Single variable-speed, bi-directional gerotor-style hydraulic motor in an adjustable housing that compensates for bristle wear; direct drive to the brush core. |
| Motor displacement | 393 cm3/rev (24 in3/rev). |
| Emissions tier | Not applicable, no combustion engine on this attachment. |
Weights
| Unit weight (base configuration) | 422 kg (930 lb) per factory work tool literature for the polypropylene bristle configuration. |
| Unit weight (alternate listings) | Some dealer listings show 430 kg (948 lb); varies by broom bristle configuration (all-polypropylene vs polypropylene/wire) and source. |
| Shipping weight | Not separately published; unit weight is the figure carried in factory and dealer literature. |
| Ground pressure | Not applicable/not published, this is a carried work tool, not a ground-bearing machine. |
Dimensions
| Overall width | 1810 mm (71 in). |
| Sweeping width | 1510 mm (59 in); some dealer listings round to 1500 mm (59.1 in). |
| Height | 793 mm (31 in). |
| Length | 1490 mm (59 in) per factory spec sheet; some dealer listings show up to 1530 mm (60.2 in), varies by source/measurement point. |
| Brush diameter | 660 mm (26 in); some listings show 665 mm (26.2 in). |
Performance
| Travel speed / gradeability | Not applicable, this is a non-self-propelled carried attachment with no travel drive of its own. |
| Sweeping direction | Bi-directional bristle rotation; sweeps and collects light debris on smooth surfaces in forward or reverse machine travel. Adjustable locking nut sets bristle down-force for dust-pan or over-the-brush sweeping. |
| Brush speed (shaft) at max flow | 220 rpm per factory work tool literature; individual dealer listings show a range of roughly 190-210 rpm, varies by configuration/source. |
| Hopper capacity (struck) | 0.42 m3 (0.55 yd3 / 14.9 ft3), rated per ISO 7546:1983 and SAE J742 FEB85. |
Service capacities (summary)
| Fuel tank | Not applicable, no onboard engine or fuel system. |
| Engine oil | Not applicable, no onboard engine. |
| Cooling system | Not applicable, no onboard engine or cooling system. |
| Required hydraulic flow | 30-86 L/min (8-23 gpm), standard-flow circuit without electrical connection. |
| Optimal hydraulic pressure | 145-235 bar (2100-3400 psi) per factory work tool literature; some dealer listings show a wider band up to 241 bar (3500 psi), varies by source. |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
BU115 fluids & capacities
| System | Capacity | Recommended fluid |
|---|---|---|
| Hydraulic drive (host carrier supplied) | No dedicated tank or reservoir on the tool itself; the broom motor runs off the carrier's hydraulic circuit. Required flow 30-83 L/min (8-22 US gpm), optimal operating pressure 145-227 bar (2100-3300 psi) | No separate fluid fill for the broom; carrier's hydraulic oil applies per the carrier's own OMM (Cat HYDO Advanced or equivalent multi-viscosity hydraulic oil, selected by carrier ambient-temperature chart) |
| Brush drive bearings (bristle-side inner and outer bearing) | Grease spec only; no fill capacity published, lubricate at scheduled grease-fitting service interval | Cat Multipurpose Grease (lithium complex base, NLGI 2); Cat Ball Bearing Grease acceptable for sealed/ball/needle bearing positions. No climate-split viscosity grades are published for this work tool |
| Pivot and mounting linkage points | Grease spec only; no fill capacity published | Cat Multipurpose Grease, NLGI 2 |
Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.
Caterpillar BU115 maintenance schedule
| Service interval | Tasks |
|---|---|
| Every 10 h |
|
| Every 50 h |
|
| Every 250 h |
|
| Every 500 h |
|
Servicing the BU115 beyond the schedule
Predictive Maintenance & Fluid Analysis
The BU115 has no reservoir of its own, so predictive care starts on the carrier side: watch the host machine's hydraulic oil condition and filtration, since debris and fine dust can work back into the auxiliary circuit through the broom's quick coupler. On the attachment, track bristle wear rate as the leading indicator — measure the swept pattern width and remaining bristle length at each interval so a drifting down-force adjustment gets caught before it accelerates core wear or overloads the motor.
Corrective & Common Repairs
Most BU115 repairs fall into three buckets: the gerotor motor, the hose/coupler set, and the bristle core. Motor case leaks usually trace to a worn shaft seal or a loose mounting bracket. Hose and quick-disconnect failures show up as pressure loss or drift at the coupler face and are replaced as a set. Uneven bristle wear or a stalling core points to bearing wear or a bent drop-pin, both serviceable without pulling hydraulic lines thanks to the drop-core design.
Overhaul & Rebuild Points
A full BU115 overhaul centers on the bristle core and its bearings, not an engine. Replace convoluted brush half-kit sections once bristle length is too short to flick debris effectively, repack or replace the core bearings on both sides of the housing, and inspect the frame and torque tube for cracking from years of down-force sweeping. Where the gerotor motor shows case scoring or persistent internal leakage, exchange or rebuild it rather than run it down to a stall.
Seasonal & Environment Servicing
Cold weather stiffens and can crack polypropylene bristles, so drain the optional water sprinkler kit lines before freezing temperatures to avoid split fittings. Hot, abrasive, dusty conditions accelerate bristle tip wear and chew through the front and side containment boots faster, so check boot condition more often in summer milling and paving work. In wet or corrosive environments, rinse debris from the coupler face and motor housing to keep the quick-attach interface and case seals from corroding.
BU115 fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| Work Tool Light – Red (steady or flashing) | Work tool hydraulic circuit is locked out; the carrier will not send flow to the broom drive motor. | Work tool lockout switch engaged, seat bar or seatbelt interlock open, or a detected hydraulic system fault on the carrier. | Seat the operator, fasten the seatbelt or lower the seat bar, confirm the work tool lockout switch is unlocked; if the light stays on, connect Cat ET to read the underlying fault. |
| Work Tool Light – Amber | Interlock override is active, allowing work tool hydraulics with the seat bar or seatbelt interlock bypassed. | Operator has engaged the interlock override to run the broom with a door or side panel open, or seat bar raised. | Confirm the override was intentional and required for the task; disengage it after use to restore normal interlock protection. |
| E875-2 (Low System Voltage) | Carrier battery or charging voltage dropped below roughly 12.0V DC for 30 seconds with the engine running. | Weak battery, loose ground, or charging system fault; low voltage can drop out work tool solenoids and the detent coil mid-sweep. | Check battery state of charge and terminal condition, inspect charging system output, clear the code and confirm voltage holds above about 12.25V before resuming work. |
| Work Tool Detent (Float) Coil Fault | The joystick detent solenoid that holds the work tool lever in continuous-flow/float position for the broom will not hold or release. | Open or shorted detent coil (spec is roughly 10 ohms), corroded joystick connector, or harness damage. | Check detent coil resistance at the joystick connector, inspect the harness for chafing near the loader arm pivot, replace the coil if out of spec. |
| High-Flow Not Engaging | Carrier will not switch the auxiliary circuit into high-flow mode, so the broom runs at low-flow speed only. | Thumbwheel or rocker control not fully displaced, or the electrical connector for the high-flow circuit at the loader arm is disconnected or damaged. | Confirm the high-flow control is at full travel, inspect the loader-arm electrical connector for the high-flow solenoid, reseat or repair as needed. |
| Auxiliary Hydraulics Inoperative (fuse/roll-switch fault) | No hydraulic flow reaches the work tool circuit; the broom will not turn at all. | Blown auxiliary hydraulics fuse or a failed auxiliary hydraulic roll/rocker switch on the joystick. | Check and replace the auxiliary hydraulics fuse, test roll switch continuity, inspect wiring back to the main harness. |
| Work Tool Circuit Relief/Overpressure Event | Work tool hydraulic pressure exceeded the circuit's main relief setting; reported main relief settings on SSL/CTL work tool circuits run around 23000 kPa (3336 psi), varies by carrier model. | Broom bristles jammed against debris or a curb, contaminated hydraulic oil, or a sticking relief valve. | Stop and clear any obstruction from the broom, check hydraulic oil condition, have the relief valve pressure-tested 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.
BU115 attachments & work tools
Product identification
The Cat BU115 is not a carrier machine but a Utility Broom work tool. It mounts to compact equipment carriers (skid steer loaders, compact track loaders, and compact wheel loaders in the 903-908 class) rather than being fitted with attachments itself.
Sweeping / bristle configuration
Offered in two bristle configurations: all-polypropylene, and combined polypropylene/steel-wire sections for tougher debris such as cold-planer spoil. Replacement brush sections let the operator switch material without replacing the whole broom body.
Size and capacity for this class
Overall width runs about 1810 mm (71.3 in) with a sweeping width in the 1500-1510 mm (59.1-59.4 in) range depending on source, and a brush diameter near 660-665 mm (26-26.2 in). Operating weight is about 430 kg (948 lb), plus roughly 40 kg (88 lb) for the optional gutter brush.
Hydraulic requirement
Direct-drive hydraulic motor, no separate gearbox. Required flow is roughly 30 L/min at the low end up to 83-86 L/min (8-22/23 gpm), with optimal pressure around 145-227 to 241 bar (2100-3300/3500 psi) depending on carrier hydraulic circuit; motor displacement is about 393-395 cm3/rev, giving brush speeds near 190-210 rpm at maximum flow. Carrier must have a standard auxiliary hydraulic circuit within this range.
Coupler / mounting system
Uses the Cat skid steer-style hydromechanical quick-attach coupler shared across skid steer loaders, multi-terrain loaders, and compact track loaders. Cat compact wheel loaders (906/907/908 class) carry a work-tool quick coupler that accepts the same skid-steer/CTL hydromechanical work tools, so the BU115 cross-fits that class without a separate adapter.
Factory options and guarding
Optional water sprinkler kit reduces airborne dust during sweeping. Optional all-steel wire gutter brush mounts to the left or right side of the broom body to pull material from gutters and pavement edges. Down-force on the bristles is adjustable for harder-duty sweeping such as clearing coarse material from a cold-planer cut.
Typical application class
Intended for smooth-surface debris clearing (streets, lots, driveways, sidewalks, factory floors) in forward or reverse travel, and for spoil removal support behind cold-planing work. It is a light-duty utility sweeper, distinct from heavier angle brooms or pickup sweepers in the same Cat broom lineup.
All BU115 assemblies by section
Every catalogued assembly group for the Caterpillar BU115. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Electrical System
249-7649 Connector As -Resistive Temperature Device
| 18***36 | Socket-Connector; (16-Ga To 18-Ga) | 24 |
| 24***49 | Connector As; -Resistive Temperature Device | 1 |
| 3E***67 | Ring-Retaining | 1 |
Frame And Body
211-9547 Frame Gp-Broom -61-In
| 21***47 | Frame Group-Broom; -61-In | 1 |
| 21***56 | Frame As | 1 |
| 21***38 | Skirt; (Front) | 1 |
211-9548 Frame Gp-Broom -75-In
| 21***48 | Frame Group-Broom; -75-In | 1 |
| 21***57 | Frame As | 1 |
| 21***39 | Skirt; (Front) | 1 |
217-6178 Frame Gp-Debris -61-In
| 16***19 | Bolt; (M24x3x180-mm) | 2 |
| 21***78 | Frame Group-Debris; -61-In | 1 |
| 21***80 | Frame As | 1 |
217-6179 Frame Gp-Debris -75-In
| 16***19 | Bolt; (M24x3x180-mm) | 2 |
| 21***79 | Frame Group-Debris; -75-In | 1 |
| 21***81 | Frame As | 1 |
Hydraulic System
256-0043 Lines Gp-Connecting
| 14***15 | Connector As | 4 |
| 15***17 | Cap-Dust | 1 |
| 15***18 | Cap-Dust | 1 |
219-1251 Motor & Lines Gp-Broom -Broom
| 06***25 | Nut-Slotted Jam | 1 |
| 21***51 | Motor & Lines Group-Broom; -Broom | 1 |
| 25***43 | Lines Group-Connecting | 1 |
Service Equipment And Supplies
219-1250 Film Gp -75-In
| 12***56 | Film; (Warning) (No Step) (On Top Of Hood Behind Cab On Each Side) (On Each Fender Flare) | 1 |
| 21***50 | Film Group; -75-In | 1 |
| 22***69 | Film-Warning; (Do Not Operate, Read Omm) | 1 |
219-1249 Film Gp -61-In
| 12***56 | Film; (Warning) (No Step) (On Top Of Hood Behind Cab On Each Side) (On Each Fender Flare) | 1 |
| 21***49 | Film Group; -61-In | 1 |
| 22***69 | Film-Warning; (Do Not Operate, Read Omm) | 1 |
267-5603 Plate & Film Gp
| 17***15 | Film; (Reflective)(Warning) | 4 |
| 26***03 | Plate & Film Group | 1 |
Work Tool Arrangement
221-1980 Broom Ar-Utility -61-In
| 15***15 | Plate-Identification | 1 |
| 16***89 | Tack-Fastener | 4 |
| 21***47 | Frame Group-Broom; -61-In | 1 |
221-1990 Broom Ar-Utility -75-In
| 15***15 | Plate-Identification | 1 |
| 16***89 | Tack-Fastener | 4 |
| 21***48 | Frame Group-Broom; -75-In | 1 |
Work Tools
219-1170 Brush Gp-Broom -61-In
| 16***69 | Kit-Brush; -Polypropylene | 1 |
| 16***70 | Kit-Brush; -Wire | 1 |
| 16***88 | Bristle As-Polypropylene | 34 |
219-1171 Brush Gp-Broom -75-In
| 16***71 | Kit-Brush; -Polypropylene | 1 |
| 16***72 | Kit-Brush; -Wire | 1 |
| 16***88 | Bristle As-Polypropylene | 40 |
242-7200 Brush Gp-Gutter
| 13***40 | Key-Square | 1 |
| 14***36 | Adapter; (Straight) (-6 Orb X -6 Orfs) | 2 |
| 14***72 | Elbow Group | 1 |
257-5229 Kit-Mounting -Gutter Brush
| 22***70 | Bracket As | 1 |
| 22***73 | Plate | 1 |
| 22***76 | Plate | 2 |
256-9335 Kit-Water Spray -Lines, Dust Control
| 00***86 | Connector-Hose (1/4-18nptf Thd) | 2 |
| 12***56 | Clamp-Hose | 10 |
| 17***92 | Coupling | 1 |
247-6742 Pump Gp-Diaphragm
| 16***63 | Motor-Electric; (12-Volt) | 1 |
| 24***42 | Pump Group-Diaphragm; -Water Spray | 1 |
| 24***23 | Head-Pump | 1 |
116-2001 Strainer Gp-Water
| 11***01 | Strainer Group-Water | 1 |
| 11***14 | Screen; (Water Tank) | 1 |
| 11***15 | Gasket | 1 |
BU115 serial number reference
The identification plate for the BU115 utility broom is mounted on the main frame/hopper weldment of the broom, near the mounting plate or side frame, so it stays readable with the tool detached from the carrier. As a hydraulically driven work tool rather than a self-propelled machine, it uses the shorter-style Cat serial format: a 3-letter prefix identifying the build/parts-catalog series followed by a sequential unit number, rather than the full 17-character machine PIN. Read the 3-letter prefix first to identify the production series, then use the sequential number to place the unit within that run. Because BU115 and BU118 share serial-prefix ranges in the parts catalog, use the full PIN and dealer lookup to confirm which model and configuration a given unit is before ordering parts.
| Prefix | Identifies | Notes |
|---|---|---|
| HJS | BU115 & BU118 Utility Broom, shared serial prefix | Covers utility broom work tools from the first HJS-prefixed unit and up. Parts catalog groupings under this prefix (cutting-edge group, broom-core/brush group, dust-control water-spray kit) are published jointly for BU115 and BU118 rather than split by model. One documented edge/brush group under this prefix is a 75 in (1900 mm) width option; since the catalog page is shared across both models, confirm which width applies to your unit. The broom is a hydraulically driven attachment (gerotor motor) with no engine of its own; power comes from the carrier machine's hydraulic system. Confirm the exact model split with your dealer using the full PIN before ordering model-specific parts. |
| LXB | BU115 & BU118 Utility Broom, shared serial prefix | Covers a production run of utility brooms listed jointly for BU115 and BU118, including a 1500 mm (59 in) sweep-width broom-core grouping and a gutter-brush mounting kit. Because the prefix is published as a combined BU115/BU118 range rather than split by model, confirm the exact model cutover point with your dealer using the full PIN before ordering model-specific parts. |
Frequently asked questions
What carriers and hydraulic flow does the BU115 need?
The BU115 mounts on skid steer loaders, compact track loaders, multi terrain loaders, and compact wheel loaders fitted with an auxiliary hydraulic circuit. It needs a flow range of 30-86 L/min (8-23 gpm) at an optimal pressure of 145-235 bar (2,100-3,400 psi). The direct-drive gerotor motor displaces 393 cm3/rev (24 in3/rev) and spins the brush core up to about 220 rpm at max flow.
What is the BU115's operating or shipping weight?
Base unit weight is 422 kg (930 lb) without options. Adding the water sprinkler kit, an all-polypropylene or all-steel wire brush core, or a bolt-on cutting edge adds to that figure, so actual shipping weight varies by configuration — confirm the built spec with your dealer for exact freight weight.
What configurations and options does the BU115 come in?
Standard bristle core is polypropylene/wire convoluted brush sections. Optional all-polypropylene core suits turf and snow work with better lift action; optional all-steel wire core suits compacted material and aggressive sweeping. An optional water sprinkler kit is available for dust suppression, and half-kit brush sections allow partial core replacement without swapping the full drum.
What BU115 owners discuss
What hydraulic flow and pressure does the BU115 need, and will it run on a standard-flow skid steer?
Does the BU115 need a two-hose hookup or a case-drain third line?
How long do the bristles actually last, and when should they be swapped?
What mounting and coupler quirks should I know about before bolting one on?
What operating habits shorten the life of the motor and bristles?
What should I check before buying a used BU115?
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
Need a specific BU115 part?
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