Caterpillar SG16
Maintenance schedule, common problems & OEM parts breakdown
The Cat SG16 is a hydraulically driven stump-grinder work tool, not a self-powered machine: it mounts to skid steers, compact track loaders, and compact wheel loaders through a standard Cat quick coupler and carries no onboard engine, hydraulic tank, or gearbox. Every function - cutter-wheel rotation, swing, extension, and depth - runs off the carrier's own hydraulic system at a standard-flow rate of roughly 42-86 L/min and 145-235 bar (2100-3400 psi). The cutting wheel measures about 547 mm (21.5 in) across and carries bolt-on, replaceable carbide teeth turned by a variable-speed, unidirectional gerotor motor. Operating weight is about 379 kg (835.6 lb). Documented since at least 2018 under the SG16B name and still sold today as the simplified SG16, it pairs in the current lineup with the higher-flow SG36 (formerly SG18B) for larger carriers, and fits compact-loader classes such as the 236, 246, 262, and 272 series across both generations of naming.
What changed across generations is the label, not the hardware: Caterpillar folded the SG16B name into SG16 as part of a broader 2024 catalog refresh that also renamed the SG18B to SG36, without a documented mechanical redesign - dimensions, hydraulic flow and pressure ranges, wheel size, and swing geometry carry over unchanged between the two names. That continuity matters in the used and parts market today: listings under either SG16B or SG16 describe the same physical tool, so buyers can cross-shop both names for the same wear parts and rebuild kits. As a relatively low-cost, engine-free attachment, the SG16 sees heavy rental and resale turnover, and its value holds up as long as the cutter wheel, gerotor motor, and coupler interface check out, since there is no engine-hours clock to inflate or deflate the asking price.
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 SG16 specifications
Engine
| Power source | No onboard engine. SG16 is a passive hydraulic work tool, driven entirely by the carrier machine's hydraulic system through a direct-drive, variable-speed, unidirectional gerotor-style hydraulic motor. |
| Motor type | Direct-drive gerotor motor, variable speed, unidirectional |
| Motor effective displacement | 80 cm³ (4.9 in³) |
| Emissions tier | Not applicable — attachment carries no engine or emissions certification; it runs off the carrier machine's hydraulics |
Weights
| Unit weight | 379 kg (835.6 lb) |
| Shipping weight | Not separately published; ships at unit weight, 379 kg (835.6 lb) |
| Ground pressure | Not applicable / not published — mounted work tool with no independent ground-bearing spec |
Dimensions
| Overall length | 1737 mm (68.4 in) |
| Overall width | 1175 mm (46.3 in) |
| Overall height (transport) | 730 mm (28.7 in) |
| Cutting wheel diameter (with teeth) | 547 mm (21.5 in) |
| Cutting wheel width (with teeth) | 83 mm (3.3 in) |
| Cutting width, full swing range | 1524 mm (60 in) |
| Cutting height, above ground | 470 mm (18.5 in) |
| Cutting depth, below ground | 521 mm (20.5 in) |
| Cutting head extension travel | 280 mm (11 in) |
Performance
| Cutting head speed at maximum flow | 993 rpm (drive shaft) at 80 L/min (21 gpm) |
| Drive shaft torque at maximum pressure | 295 N·m (218 lb-ft) at 230 bar (3,336 psi) |
| Cutting head swing range | 70°, electro-hydraulic control from the carrier's cab |
| Cutting head extension control | Hydraulic, controlled from the carrier's cab |
| Cutting depth control | Manual adjustment on this model (hydraulic depth control is reserved for the larger sibling in the stump-grinder line) |
| Ground engaging teeth | 32 bolt-on, replaceable carbide teeth, 12.7 mm (0.5 in) square shank |
| Required hydraulics / interface | Standard-flow circuit, skid steer quick-coupler interface |
| Carrier compatibility | Cat skid steer loaders, compact track loaders and compact wheel loaders in the 216B3 through 299D3 range, plus 903-908 compact wheel loaders; exact availability varies by region and dealer |
Service capacities (summary)
| Fuel tank | Not applicable — no onboard engine |
| Hydraulic system (attachment) | No dedicated reservoir; draws from the carrier's hydraulic circuit. Requires 42-86 L/min (11-23 gpm) at 145-235 bar (2,100-3,400 psi) |
| Engine oil | Not applicable — no onboard engine |
| Cooling system | Not applicable — cooling is handled through the carrier machine's hydraulic system |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
SG16 fluids & capacities
| System | Capacity | Recommended fluid |
|---|---|---|
| Cutting wheel drive (direct-drive gerotor motor) | No dedicated reservoir. Direct-drive design — no gearbox or gear oil sump on the tool itself. | None owned by the work tool. Motor runs on the host machine's hydraulic oil; no separate fluid specification for the SG16 drive. |
| Hydraulic power supply (swing, extension, cutting wheel — all functions) | Not a tool-owned capacity. Draws from the host carrier's hydraulic tank. Tool requires 42–86 L/min (11–23 US gpm) flow at 145–235 bar (2100–3400 psi) from the host machine. | Whatever hydraulic oil the host machine's own OMM specifies (typically Cat HYDO Advanced or equivalent TDTO-type fluid on Cat carriers). The SG16 has no independent hydraulic fluid spec — follow the carrier's chart, not the tool's. |
| Engine crankcase | Not applicable — the SG16 has no engine. | Not applicable. |
| Cooling system | Not applicable — the SG16 has no engine or radiator. | Not applicable. |
| Fuel tank | Not applicable — the SG16 has no fuel system. | Not applicable. |
| Transmission / final drives / axles | Not applicable — the SG16 is a passive hydraulic attachment with no powertrain, final drive, or axle compartments of its own. | Not applicable. |
| Grease points (swing pivot, wheel-head bearings, extension slides, wear bushings) | No published fill volume — grease to refusal at each fitting. Service interval not documented in available sources; verify against the OMM for the exact serial range. | Standard Cat multi-purpose EP grease (NLGI-graded per ambient temperature), consistent with Cat's general work-tool lubrication line. No SG16-specific climate/viscosity breakout was found — treat as the general-purpose grease chart until confirmed against the tool's own OMM. |
Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.
Caterpillar SG16 maintenance schedule
| Service interval | Tasks |
|---|---|
| Every 50 h |
|
| Every 250 h |
|
| Every 500 h |
|
| Every 1,000 h |
|
| Every 2,000 h |
|
| Every 4,000 h |
|
Servicing the SG16 beyond the schedule
Predictive Maintenance and Fluid Analysis
Since the SG16 carries no reservoir of its own, lean on the carrier's hydraulic oil-sample program: metal fines or gerotor debris turning up in the carrier's filter often trace back to wear inside the grinder motor, not the carrier pump. Track cutter-wheel bearing end-float, hose skin temperature at the quick-disconnects, and swing-cylinder drift over time as early warning signs. Catching gerotor scoring or bearing play before it worsens keeps a customer's carrier from being sidelined mid-job.
Corrective and Common Repairs
Most callbacks trace to broken or missing carbide teeth, a scored gerotor motor from running the tool below its rated carrier flow, or a leaking quick-disconnect at the carrier interface. Bent stand feet from grinding on uneven ground and worn coupler wedge pins causing attachment rattle come next. With no engine or ECM to throw a fault code, diagnosis stays mechanical: a tooth wear gauge, a bearing play check, and a hose and fitting leak-down test cover most complaints.
Overhaul and Rebuild Points
A full rebuild centers on three wear assemblies: the gerotor drive motor (shaft seal and case-drain wear), the cutter-wheel bearing and hub, and the swing cylinder pins and bushings. Rebuild timing tracks carrier hours logged with the tool mounted, not a standalone clock, since the attachment has no engine of its own. Reuse the coupler frame and structural swing arm if they test crack-free, but replace hoses as a set at overhaul since individual hose failure is the top cause of unplanned downtime.
Seasonal and Environment Servicing
Frozen ground, root-bound stumps, and rocky sites accelerate carbide tooth chipping and stand-foot wear, so shorten inspection intervals through winter grinding season. Wet or sandy jobsites pack debris into the swing-arm pivots and coupler wedge, so flush and re-grease those points more often than the standard interval calls for. Between seasons, store the tool with the cutter wheel supported off the ground and cap the hydraulic quick-disconnects to keep contamination out of the carrier's open ports.
SG16 fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| No SG16 fault codes (passive attachment) | The SG16 has no engine, ECM, or onboard electronic control system of its own. It is a direct-drive hydraulic stump grinder that runs entirely off the carrier machine's hydraulic supply, with swing and extension actuated by an electro-hydraulic valve operated from the carrier's cab controls. | Not applicable - the tool has no self-diagnostic capability and cannot generate or store a fault code. | Diagnose grinding wheel or swing/extension problems as a hydraulic-circuit issue on the carrier, not as a work-tool ECM fault. |
| Hydraulics alert indicator (red, with audible alarm) | Carrier hydraulic oil temperature has exceeded the safe operating range. | Sustained high-load grinding pushes return oil past the carrier's hydraulic cooler capacity; also low hydraulic fluid level, blocked cooler, or a flow setting mismatched to the SG16's optimal range. | Stop grinding, idle the carrier to let hydraulic oil cool, then check fluid level and cooler fins; confirm the carrier's auxiliary flow setting matches the SG16 spec plate before resuming. |
| Work tool system alert indicator (red) | Hydraulic lockout is active, disabling the SG16 swing, extension, and wheel drive circuits. | Operator engaged the hydraulic lockout switch, a required safety step whenever leaving the seat or transporting the machine with the SG16 attached. | Confirm the operator is seated with restraint engaged, then return the lockout switch to the active (mid) position to restore hydraulic function to the attachment. |
| Work tool system alert indicator (amber) | Seat bar or seatbelt interlock override is active while the SG16 is powered. | Operator manually bypassed the interlock to run the attachment with the seat bar raised, typically during setup or troubleshooting. | Verify the override is intentional and required; lower the seat bar and clear the override for normal operation once finished. |
| Auxiliary hydraulic flow/pressure warning (carrier-dependent) | Carrier's auxiliary hydraulic circuit is outside the flow or pressure range the SG16 needs for correct cutting-wheel speed. | Continuous-flow aux circuit not switched on or set to match the SG16's rated flow window, a partially engaged quick coupler, or a restricted hydraulic line. | Check the coupler is fully locked, confirm the carrier's aux hydraulic setting against the SG16 flow specification, and inspect hoses for kinks or restriction. |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
SG16 attachments & work tools
Work tool type & size class
SG16 is a hydraulically driven stump grinder attachment sized for the compact/mid-size skid steer and compact track loader class, extending down into Cat's small wheel loader range. It pairs a direct-drive cutting wheel with pivoting stand feet so the host machine can grind stumps to a set depth below grade.
Coupler / mounting system
Mounts to the carrier's standard quick-coupler plate, with an opposing-edge coupler design that locks the tool to the loader arms for fast tool-to-tool changeout. Heavy-duty, dual-height pivoting stand feet are field-adjustable to match a given carrier's coupler-to-ground height and tire or track size.
Hydraulic circuit / kit
Runs on the carrier's standard-flow auxiliary hydraulic circuit, roughly 42-86 L/min (11-23 gpm) at 145-235 bar (2100-3400 psi). A gerotor-style, variable-speed, unidirectional motor direct-drives the wheel; swing and extension of the cutting head are hydraulically actuated and cab-controlled through an electro-hydraulic valve, so no add-on control kit is needed beyond the carrier's standard or high-flow auxiliary circuit.
Cutting head & wheel
Cutting wheel measures about 546 mm (21.5 in) in diameter and roughly 84 mm (3.3 in) wide, fitted with bolt-on, field-replaceable carbide teeth. Wheel speed reaches about 993 rpm at maximum flow, delivering roughly 295 N·m (217.6 lb-ft) of drive-shaft torque at maximum pressure.
Grinding range / geometry
Cutting head reaches about 521 mm (20.5 in) below grade and 470 mm (18.5 in) above grade, with roughly 279 mm (11 in) of head extension and a 70-degree hydraulic swing that gives about 1.52 m (60 in) of full-swing cutting width without repositioning the carrier.
Carrier compatibility
Current factory compatibility spans Cat skid steer and compact track loaders from the 216-226 class up through the 289-299 class, plus the small wheel loader range (900-series). Exact model list and hydraulic kit fitment vary by region, carrier generation, and production year — confirm current fit with a dealer before ordering.
Size-class siblings
SG16 sits at the low-flow end of Cat's stump-grinder line. A larger sibling shares the same cutting-wheel diameter and cutting depth but steps up to a high-flow hydraulic circuit for bigger carriers — cutting geometry stays similar across the class, with carrier hydraulic capacity as the main differentiator. An earlier production generation of this tool (documented on some dealer pages under a related suffix) listed a shorter, older carrier compatibility range; treat exact carrier fit as varying by production year.
Stability & operator control features
Dual-height pivoting stand feet plant the tool during grinding and adjust for different carrier tire or track heights. Swing, extension, and depth are all cab-controlled hydraulically, keeping the operator off the ground and away from the wheel during operation.
All SG16 assemblies by section
Every catalogued assembly group for the Caterpillar SG16. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Frame And Body
173-9317 Frame Gp-Stump Grinder
| 00***00 | Ring-Snap | 6 |
| 14***03 | Washer-Thrust; (45.3x65x5-mm Thk), Plug; Replaces 420648a1, Plug | 1 |
| 16***50 | Frame As; (Front) | 1 |
173-9352 Link Gp-Adjustable -Depth Adjustment
| 00***00 | Ring-Snap | 2 |
| 17***52 | Link Group-Adjustable; -Depth Adjustment | 1 |
| 22***22 | Link | 1 |
173-9346 Mounting Gp-Motor
| 17***46 | Mounting Group-Motor | 1 |
| 22***85 | Plate | 2 |
| 6V***87 | Locknut; (M12x1.75-Thd) | 4 |
Hydraulic System
224-4482 Cylinder Gp-Hydraulic -Extension/Depth
| 22***82 | Cylinder Group-Hydraulic; -Extension/Depth | 1 |
| 22***83 | Kit-Seal | 1 |
224-4480 Cylinder Gp-Hydraulic -Swing
| 22***80 | Cylinder Group-Hydraulic; -Swing | 1 |
| 22***81 | Kit-Seal | 1 |
| 3B***89 | Fitting-Grease; (Fan And Alternator Drive) | 1 |
173-9349 Hydraulic Ar
| 17***25 | Lines Group-Connecting; -Control Valve | 1 |
| 17***49 | Hydraulic Ar | 1 |
| 17***55 | Lines Group-Motor | 1 |
173-9338 Hydraulic Ar
| 15***70 | Kit-Connecting Plug; (2-Pin)(Engine Sensor Wiring Harness) | 5 |
| 16***94 | Harness As-Work Tool | 1 |
| 17***38 | Hydraulic Ar | 1 |
172-4825 Lines Gp-Connecting -Control Valve
| 15***94 | Coupler As-Quick Disconnect; (Female)(Quick Disconnect) | 1 |
| 15***95 | Fitting As; (Quick Disconnect, Male) | 1 |
| 17***03 | Hose As | 1 |
173-9356 Lines Gp-Cylinder -Extension
| 17***14 | Hose As | 1 |
| 17***15 | Hose As | 1 |
| 17***56 | Lines Group-Cylinder; -Extension | 1 |
173-9358 Lines Gp-Cylinder -Swing
| 17***16 | Hose As | 1 |
| 17***18 | Hose As | 1 |
| 17***19 | Hose As | 2 |
173-9355 Lines Gp-Motor
| 17***11 | Hose As | 1 |
| 17***12 | Hose As | 1 |
| 17***55 | Lines Group-Motor | 1 |
224-4500 Manifold Gp-Control
| 10***08 | Kit-Seal; (Solenoid Valve, Quick Steer) | 4 |
| 14***32 | Seal Kit; (Includes O-Rings, Backup Rings) | 1 |
| 14***33 | Valve Group-Check; (Tank/Supply) | 1 |
224-3126 Motor Gp-Gerotor
| 06***25 | Nut-Slotted Jam | 1 |
| 17***46 | Kit-Seal | 1 |
| 22***26 | Motor Group-Gerotor | 1 |
224-4498 Mounting Gp-Manifold
| 22***98 | Mounting Group-Manifold | 1 |
| 22***99 | Plate As | 1 |
| 8T***97 | Nut-Weld; (M12x1.75-Thd) | 2 |
Service Equipment And Supplies
185-3556 Plate & Film Gp
| 12***56 | Film; (Warning) (No Step) (On Top Of Hood Behind Cab On Each Side) (On Each Fender Flare) | 2 |
| 15***62 | Film-Information; (Tie-Down Location) | 2 |
| 15***36 | Film-Warning; (Read Operation Manual) | 1 |
Work Tool Arrangement
163-9449 Stump Grinder Ar
| 16***49 | Stump Grinder Ar | 1 |
| 17***49 | Hydraulic Ar | 1 |
| 17***52 | Link Group-Adjustable; -Depth Adjustment | 1 |
173-9316 Stump Grinder Ar
| 17***16 | Stump Grinder Ar | 1 |
| 17***17 | Frame Group-Stump Grinder | 1 |
| 17***28 | Wheel Group-Stump Grinder | 1 |
Work Tools
173-9328 Wheel Gp-Stump Grinder
| 01***74 | Bolt-Socket Head | 32 |
| 0T***98 | Bolt; (1/2-20x0.875-In) | 5 |
| 17***28 | Wheel Group-Stump Grinder | 1 |
SG16 serial number reference
The PIN plate on the SG16 is a small metal tag riveted to the attachment frame, near the quick coupler mount plate or hydraulic motor housing, since the tool has no engine of its own. Read the first three characters as the plant/model prefix (identifies this as an SG16 build) and the digits that follow as the sequential unit number within that prefix run.
| Prefix | Identifies | Notes |
|---|---|---|
| WMA | SG16 stump grinder (base configuration) | Confirmed on a 2022-built unit (WMA00286), explicitly titled Caterpillar SG16 stump grinder, not SG16B. The SG16 is hydraulically driven with no onboard engine; it draws hydraulic flow from the host skid steer, compact track loader, or multi terrain loader (optimal flow roughly 42-86 L/min / 11-23 gpm at 145-235 bar / 2100-3400 psi), so this prefix identifies the grinder attachment itself, not a power unit. Only one confirmed serial has been located publicly - treat the exact start/end of the WMA run as unconfirmed and verify specific units with your dealer. |
Frequently asked questions
What engine does the Cat SG16 stump grinder run?
None. The SG16 has no engine of its own - it is a passive hydraulic work tool that draws all of its power from the carrier machine's hydraulic system, at a standard-flow rate of about 42-86 L/min and 145-235 bar (2100-3400 psi). The carrier's engine does the work; the SG16 just converts that hydraulic flow into cutter-wheel rotation, swing, and extension.
What is the operating weight of the Cat SG16?
About 379 kg (835.6 lb). That figure is the attachment alone, since it carries no fuel, oil reservoir, or engine to add to the total.
What replaced the Cat SG16?
Nothing has superseded it outright - the SG16 name is itself the direct continuation of the earlier SG16B, with Caterpillar dropping the B suffix during a 2024 catalog refresh rather than issuing a mechanical redesign. Its higher-flow sibling, sold first as SG18B and now as SG36, remains the step-up option for larger carriers.
What SG16 owners discuss
What hydraulic flow and pressure does the carrier need to supply, and what happens if it's mismatched?
How much wear do the carbide teeth take, and when do they need replacing?
What wear shows up in the cutter wheel bearings and swing arm, and how do owners check it?
What quirks show up in the SG16's electro-hydraulic swing/extension controls?
What should the coupler fit look like, and what wears there?
What should you check when buying a used SG16?
Does the SG16 use the same drive setup as the rest of Cat's stump grinder line?
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
Need a specific SG16 part?
Search live OEM part data, check fitment, and cross-reference alternatives with Heavy Parts AI.