Why T6C, T6D, and T6E Are Often Confused on the Cross-Reference Desk

The three T6-series single pump cartridges look almost identical at a glance: same outline, same rotor diameter, same SAE J744 / ISO 3019 mounting flange options, same type-1 NBR seal as the standard shipping compound. The confusion comes from the part-numbering system, not the parts themselves — Denison (and the Vickers / Parker / Veljan aftermarket rebuilders that copied the catalog) use three different code families for the same physical cartridge-kit envelope:

- T6C displacement codes use the B-prefix family: B03, B05, B06, B08, B10, B12, B14, B17, B20, B22, B25, B28, B31 (5–31 mL/rev). S24 prefix S24-1xxxx. – T6D displacement codes split across two sub-families. The lower half (14–31 mL/rev) reuses the B-prefix from T6C. The upper half (35–61 mL/rev) uses no prefix: 035, 038, 042, 045, 050, 061. S24 prefix S24-2xxxx and S24-3xxxx. – T6E displacement codes use no prefix at all: 042, 045, 050, 052, 057, 062, 066, 072, 085 (66–136 mL/rev). S24 prefix S24-6xxxx and S24-69xxx.

The trap is that the same displacement number means different physical sizes across the three series — T6C-014 is 14 mL/rev at a smaller envelope, T6D-014 is the same 14 mL/rev at a longer cartridge, and T6E-042 is 42 mL/rev at the largest envelope. A part number that has been transcribed wrong across the three families by even one digit lands a dimensionally incorrect cartridge kit that will not drop into the original pump body.

The second and third confusion sources are port connection and shaft option. T6C ships with both SAE 4-bolt flange and BSPP / NPT threaded ports; T6D and T6E drop threaded ports above 66 mL/rev because the port physically cannot fit inside the cartridge housing. T6C accepts standard SAE J744 splined shafts plus keyed shafts; T6E drops SAE splined shafts entirely and ships only with heavy-duty keyed shafts. A buyer requesting “T6D threaded ports at 045″ or “T6E with SAE splined shaft” is asking for a configuration that was never catalogued.

Cross-referencing correctly is therefore a three-axis lookup — displacement code, port-connection code, and shaft code — plus the seal compound (NBR is standard, FKM is the high-temperature upgrade) and the rotation direction (right-hand clockwise vs left-hand counter-clockwise). The S24 part number encodes all five, and a complete cross-reference can be reversed from the S24 string in seconds.

For the cross-reference frameworks that govern this lookup, ISO 4413 covers hydraulic fluid power general rules for systems and components, and ISO 4391 covers hydraulic fluid power cylinders, both of which the T6-series cross-reference desk references when a buyer asks for the standard that underwrites a particular dimension. For hydraulic fluid cleanliness requirements, ISO 4406 is the governing cleanliness code standard.

Decoding the T6 Series Nameplate — Displacement, Mount, and Seal Codes

A typical Denison T6 series single pump follows this nameplate structure:

T6 C C 022 B S R 02 C 1 10

Reading left to right:

- T6 — series (T6C, T6D, or T6E). – C / D / E — second letter denotes the displacement family and the envelope size. – Third letter (C, D, E) — the pump type: C = single cartridge, D = double cartridge, E = triple cartridge (only relevant for T6GCC, T6DCC, T6EEC combos). – 022 — geometric displacement in cm³/rev × 10. So 022 = 22 mL/rev; 085 = 85 mL/rev. – B — shaft type (or omitted for heavy-duty keyed). B = standard SAE keyed, omitted = heavy-duty keyed. – S — installation flange: S = SAE C J744 flange, omitted = ISO 3019 industrial flange. – R — rotation: R = right-hand clockwise (viewed from shaft end), L = left-hand counter-clockwise. – 02 — port connection: 02 = SAE 4-bolt flange, 00 / 01 = threaded, 10 / 11 = flange with metric threads. – C — design number (internal Denison iteration; aftermarket rebuilders usually re-use the same C). – 1 — sealing level: 1 = NBR (Nitrile) for standard mineral oil, 5 = FKM (Fluoroelastomer) for high-temperature or synthetic fluid. – 0 — port dimensions: 0 = standard SAE sizes, 1 = metric equivalents.

For the standards that govern the seal compound choice and the port connection, the SAE J744 standard covers hydraulic pump and motor mounting flanges, SAE J518 covers hydraulic flange tube, and the SAE J1273 standard covers recommended practices for hydraulic hose assemblies. For the rotation direction reference, the SAE J745 standard establishes the convention for hydraulic pump and motor rotation direction as viewed from the shaft end.

For the S24 part-number family that aftermarket distributors and cross-reference platforms use, the format is similar but more compact:

- S24-25564 = T6C series, displacement 17 mL/rev, NBR seal, threaded ports. – S24-10756 = T6C series, displacement 10 mL/rev, FKM seal, threaded ports. – S24-26359 = T6C series, displacement 22 mL/rev, FKM seal, SAE flange ports. – S24-10721 = T6C series, displacement 5 mL/rev, NBR seal, threaded ports. – S24-10739 = T6C series, displacement 14 mL/rev, NBR seal, SAE flange ports. – S24-10181 = T6E series, displacement 72 mL/rev, NBR seal, SAE flange ports.

The S24 catalog (the Denison T6C Cartridge Kit S24 part numbers product listing for T6C, and the S24-10181 T6E vane cartridge listing for T6E) lists both families in parallel, and the T6 Cartridge Kit Range page groups them under the same parent category. A buyer who pulls a nameplate off a failed cartridge and translates to the S24 string in the table below has a defensible cross-reference for the aftermarket replacement.

Three rules resolve most cross-reference disputes:

1. Same displacement, different envelope: a T6C-014 (22 mL/rev) and T6D-014 (22 mL/rev) deliver the same flow at the same pressure; the difference is the cartridge length and the port size. The T6C uses the smaller cartridge body, the T6D uses the larger. They are not interchangeable in the same pump housing.

2. Step-up moves the port: moving from T6C to T6D at the same displacement code means the port size grows from 1″ to 1-1/4″ SAE 4-bolt. The pump housing flange pattern does not change, but the suction and pressure port holes do. The cartridge kit itself is dimensionally different.

3. T6E drops threaded ports entirely: at displacements 042 mL/rev and above in T6E, the only port option is SAE 4-bolt flange. A buyer specifying “T6E-072 with 1-1/4″ threaded ports” is asking for a configuration that was never catalogued.

If a buyer has the original part number and cannot locate it in the matrix above, the safer path is to forward the original number plus a nameplate photograph to the Order by Part Number form on the contact page and request a written cross-reference confirmation from Vicks Hydraulic — this avoids the cost of an incorrect cartridge kit landed at the buyer’s dock.

For marine / offshore installations, the relevant classification society rules apply. DNV rules for maritime cover the certification of hydraulic systems installed on classed vessels, Lloyd’s Register rules cover the same scope for LR-classed vessels, and American Bureau of Shipping covers ABS-classed vessels and offshore units. For Chinese-flag vessels and offshore units, China Classification Society (CCS) rules apply. For EU-flagged vessels, the Bureau Veritas marine rules apply.

When a Cartridge Kit Replacement Beats a Full Pump Replacement

The cartridge-kit replacement is the correct repair when the failure is internal to the cartridge (cam ring wear, vane tip burnishing, rotor scoring, balance plate erosion) but the pump housing, shaft, and mounting flange are still in tolerance. The cost ratio is typically one-quarter to one-fifth: a full T6C pump replacement lands at a higher per-piece price; a T6C cartridge kit lands at roughly that figure’s inverse fraction. For a T6E-072 the per-piece gap is even wider.

Three diagnostic checkpoints decide cartridge-kit replacement vs full pump replacement:

- Shaft radial play: with the cartridge removed, dial-indicator the shaft at the seal location. Acceptable radial play is ≤ 0.05 mm at the seal journal. Above 0.10 mm indicates bushing wear and the pump housing must be replaced. – Port-face flatness: lay the housing on a surface plate and feel the port-face mating surface. Any step greater than 0.03 mm across the port-face diameter indicates housing distortion and disqualifies the housing for cartridge-kit reuse. – Mounting flange perpendicularity: dial-indicator the mounting flange face against the shaft axis. Acceptable is ≤ 0.05 mm TIR (total indicator reading) across the flange diameter. Above this, the rebuilt cartridge will load asymmetrically and fail within 500 hours.

If all three checkpoints pass, the cartridge-kit replacement is the right repair and a 2–4 hour rebuild brings the pump back to full spec. If any checkpoint fails, the full pump replacement is the lower total-cost option — rebuilding a worn housing into a new cartridge kits out the next failure at the housing-cam-ring interface.

A buyer who stocks 3–5 T6C cartridge kits across the displacement codes used in the fleet and clear most failures on a same-day turnaround. Stocking full T6C pumps at every displacement is a much larger working-capital tie-up. The cartridge-kit model is therefore the right answer for high-fleet, high-failure-rate environments even when the full-pump replacement would be the cheaper option for any single failure.

For the vane-pump working principles that the rebuild procedure rests on, Hydraulics & Pneumatics covers the cam-ring-and-vane geometry that the T6 cartridge uses, and SAE International provides the design and rating conventions that hydraulic pump catalogs reference. For the broader hydraulic pump taxonomy that places vane pumps alongside piston and gear pumps, Bosch Rexroth hydraulics covers the comparison that helps a buyer decide whether a vane pump is the right architecture for the application at all.

The Rebuild Procedure — Disassembly, Inspection, and Reassembly

The T6-series cartridge-kit rebuild fits inside a 2–4 hour window for a single experienced technician with a clean bench, a torque wrench calibrated to ±4 %, and a parts-cleaning station. The procedure is series-agnostic — T6C, T6D, and T6E use the same rebuild steps; the differences are cartridge length, port-face bolt size, and torque values (T6E heavier). The five-phase procedure below is the workshop standard.

Phase 1 — Depressurize, drain, and remove

Close the suction and discharge isolation valves (or block the circuit upstream), then crack the case drain line to confirm zero residual pressure. Disconnect the suction and discharge lines, cap the open ports with plastic plugs, and unbolt the pump from the mounting bracket. Place the pump on the bench with the shaft horizontal.

Phase 2 — Disassemble the cartridge

Undo the four end-cover bolts in a cross pattern (1-3-2-4) to release the cover spring load evenly. Lift the end cover straight off without prying sideways — the cover-to-housing mating surface is precision-lapped and any side-load scores the face. Withdraw the cartridge sub-assembly by hand: rotor + vanes + cam ring + balance plate held together by the dowel pins lifts out as one piece. Remove the balance plate bolts (6 × M6 / 6 × M8 / 8 × M10 for T6C / T6D / T6E), slide the rotor with vanes out of the cam ring. Note the orientation: the rotor has a marked “shaft end” face; install the new vanes with the same orientation.

Phase 3 — Inspect every component

Four inspection items:

- Cam ring: check the inner bore for wear pattern. Acceptable is a uniform matte finish. Any scoring deeper than 0.05 mm, any discoloration in a band around the port-overlap zone, or any chip at the port edge is a reject. The cam ring is the most expensive component in the cartridge kit and the most common single failure mode. – Rotor: check the vane slot walls for burrs or scoring. Light polishing with 600-grit is acceptable; any vane slot wall that has lost more than 0.02 mm of material is a reject. – Vanes: inspect the tip edges for burnishing (mirror finish) or chipping. Any vane with tip wear greater than 0.5 mm or any chip is a reject. Replace the vane set as a complete set, never individually — mixing new and used vanes creates uneven port overlap and the rebuild fails within the first 200 hours. – Balance plate: check the balance land (the small raised pads opposite the port-overlap zone) for erosion. Any pitting deeper than 0.02 mm or any land that has lost more than 0.05 mm of height is a reject.

Phase 4 — Reassemble with new vanes and seals

Install the new vane set into the rotor slots. Place the rotor into the cam ring with the marked face toward the shaft end. Install the balance plate, align the dowel pins, and torque the bolts in two passes — first pass to 50 % of final torque in a cross pattern, second pass to 100 % in the same cross pattern. Final torque values:

- T6C balance plate bolts: 18–22 Nm (M6) – T6D balance plate bolts: 35–42 Nm (M8) – T6E balance plate bolts: 70–85 Nm (M10)

Install new NBR (or FKM) cartridge seals on the outer diameter of the cartridge, lightly greased with the system fluid. Slide the rebuilt cartridge back into the housing, replace the end cover, and torque the end-cover bolts to 28–32 Nm (T6C) / 45–52 Nm (T6D) / 80–95 Nm (T6E).

Phase 5 — Pre-fill, install, and bench-test

Before connecting to the host circuit, pre-fill the pump housing through the case drain port with clean system fluid until fluid appears at the suction port. This eliminates the dry-start failure mode that destroys a freshly rebuilt cartridge in the first 30 seconds of operation. Connect the suction and discharge lines, torque the port bolts to the system-side specification, and run the bench-test sequence below before returning to service.

Bench-Test Protocol After the Rebuild

A rebuilt T6 cartridge should not be returned to service without a 30-minute bench test under load. The minimum bench setup: a calibrated test rig with a 0.25 % accuracy pressure transducer on the discharge port, a variable-flow loading valve, a flow meter on the return line, and a 30 L reservoir of clean system fluid at 46 cSt viscosity.

### Test sequence

1. No-load spin-up (5 minutes): run the pump at 1,200 rpm with zero discharge pressure. Confirm the pump spins freely, the case drain flow is ≤ 2 L/min, and the pump temperature stabilizes within 5 °C of the reservoir temperature. Any grinding noise, any case drain flow above 3 L/min, or any temperature rise above 10 °C is a stop and re-inspect.

2. Pressure ramp (10 minutes): ramp the discharge pressure from zero to rated maximum continuous pressure in 25-bar increments, dwelling 30 seconds at each step. At each step, log the actual flow and the case drain flow. The acceptance band: actual flow within ±5 % of the nameplate rating at rated pressure, case drain flow within ±0.5 L/min of the no-load reading.

3. Hot hold (10 minutes): hold the pump at rated maximum continuous pressure and 1,500 rpm for 10 minutes. Log the pump case temperature every 60 seconds. The acceptance band: temperature rise ≤ 25 °C above the reservoir, no visible leakage at the shaft seal, no audible change in pump noise.

4. Rated performance verification (5 minutes): set the pump at rated speed (1,500 rpm) and rated pressure. Take three flow readings 30 seconds apart. The acceptance band: flow readings within ±2 % of each other (this catches internal leakage that has not yet manifested as case drain flow drift).

A pump that passes all four steps is ready for return to service. A pump that fails any step is disassembled again and the failed component identified and replaced — typically the cam ring or the vane set.

For the torque-wrench calibration standard referenced in the rebuild procedure, ISO 6789 governs the requirements for hand torque tools. For the fluid sampling and cleanliness verification referenced in the bench-test sequence, ISO 4021 covers hydraulic fluid power — particle contamination extraction and analysis methods.

The rebuild record should accompany the pump back to the host circuit: original part number, replacement part numbers used (cartridge kit, seals), date, technician ID, and bench-test results. This is the documentation layer that builds the case for the cartridge-kit replacement model over the full-pump replacement at fleet level — a five-year history of rebuild records makes the next failure cheaper to diagnose and cheaper to repair.

Failure-Mode Patterns and What They Tell the Service Workshop

T6 cartridge failures fall into five repeatable modes, each with a diagnostic signature that points to a specific cause:

- Cam ring wear at the port overlap: presents as a gradual loss of flow at rated speed. Cause is fluid-borne particulate above ISO 4406 code 18/15/12 (the cleanliness standard for hydraulic fluid). Fix is a cam ring replacement plus a fluid filtration review upstream.

- Vane tip burnishing: presents as a sharp drop in flow combined with a sharp rise in case drain flow. Cause is typically a momentary overload event (system pressure spike above the rated peak) or sustained operation at case drain temperatures above 95 °C. Fix is a complete vane set replacement plus a review of system pressure spikes and case drain cooler sizing.

- Rotor slot scoring: presents as a steady loss of volumetric efficiency combined with metal particles in the case drain. Cause is rotor-to-cam ring contact due to bearing failure or to an axial load event (system side-load on the shaft). Fix is a complete cartridge replacement plus a shaft and bearing inspection.

- Balance plate erosion: presents as a steady loss of pressure capability combined with high case drain flow. Cause is sustained operation at discharge pressures above the rated maximum continuous. Fix is balance plate replacement plus a review of system pressure relief settings.

- Shaft seal leakage: presents as visible oil at the shaft seal location. Cause is seal wear or a plugged case drain line that has pressurized the cartridge housing. Fix is seal replacement plus a case drain line clearance check.

Each of these five modes is diagnosable in 30 minutes on the bench. The cross-reference matrix earlier in the article gives the rebuild kit numbers for each failure mode. A workshop that runs a 30-minute bench diagnostic before quoting a repair can commit to a same-day turnaround for any of the five modes with the cartridge-kit replacements in stock.

For the bench-test instrumentation standards that the rebuild bench follows, SAE J1115 covers hydraulic system test methods for industrial equipment, and SAE J1165 covers the documentation requirements for hydraulic system test reports. For the failure-mode reference that supports the diagnostic patterns, SAE J1739 establishes the application of failure modes and effects analysis to hydraulic systems.

Buyer-Side Specification Checklist for Cross-Border Cartridge Kit Orders

When ordering a T6-series cartridge kit from a Chinese aftermarket rebuilder (Vicks Hydraulic or equivalent) into a European, North American, or Asian destination market, the specification checklist below is the minimum that protects the buyer from a wrong cross-reference:

Eight items to include in the RFQ

1. Original part number: the OEM Denison S24 string from the nameplate, or the original Denison nameplate string (T6CC017BSR02C110 format), or the Vickers / Parker equivalent if the pump was supplied under a different brand. A photograph of the nameplate is the fastest path.

2. Displacement code: confirmed against the cross-reference matrix above. If the buyer is uncertain between T6C and T6D at the same displacement code, the housing dimensions differentiate — measuring the cartridge length on the removed cartridge resolves it.

3. Port connection: SAE 4-bolt flange size, or BSPP / NPT thread size and pitch, or metric thread size and pitch. Specify “SAE J518 code 61 flange” or “SAE J518 code 62 flange” (the high-pressure variant) explicitly.

4. Shaft option: SAE J744 splined (and the spline count), heavy-duty keyed (and the key width), or tapered (rare, only on legacy installations).

5. Seal compound: NBR (standard, mineral oil, ≤ 80 °C) or FKM (high-temperature, synthetic fluid, ≤ 120 °C).

6. Rotation direction: right-hand clockwise (viewed from the shaft end) or left-hand counter-clockwise. This is direction-of-rotation-sensitive — a wrong rotation binds the internal balance plate on the first startup.

7. Target working pressure and duty cycle: continuous pressure at the typical duty cycle, plus the maximum intermittent pressure and the maximum rated speed. The rebuilder confirms that the requested displacement is rated for the target pressure.

8. Documentation required: per-piece dimensional inspection report, material certificates for the cam ring and rotor, seal batch traceability, and the per-piece bench-test results. For marine / offshore (CCS, DNV, ABS, BV, LR) applications, the documentation set extends to include the relevant classification society certificate.

Why all eight matter

A buyer who ships the eight items above to the rebuilder in a single email at the RFQ stage gets a defensible quote in 24 hours. A buyer who ships only the OEM part number risks a wrong cross-reference at the port connection or the shaft — the rebuild kit is dimensionally right but physically will not drop into the pump housing, and the cost of the wrong shipment plus the return plus the correct re-shipment far exceeds the cost of the rebuild kit itself.

Frequently Asked Questions