Three SKUs on one 330 mm 6120M pack — do not order only the plate
A travel clutch is three jobs on one shaft: the disc that carries torque, the cover that clamps it, and the release bearing that opens the pack. Buying one without the others is how the next callback is scheduled. This page compares the three SEROC lines seeded for a 330 mm John Deere 6120M pack — SRC-CL-D330, SRC-CL-C330 and SRC-CL-RB28 — so a requisition names the part that actually failed, not 'a clutch'.
What each SKU is for
SRC-CL-D330 is the organic driven plate: 330 mm lining outside diameter, 21-tooth spline, 28.6 mm major diameter. It is the friction surface. If the lining is to the rivets, glazed from oil, or the damper springs are collapsed, this is the line. It is not a dual-plate PTO pack and it is not a 6R clutch. A cover photograph will not confirm spline count.
SRC-CL-C330 is the cover assembly that clamps that 330 mm single-plate disc, mechanical release. Height, lever wear and clamp load live here. A new disc against a tired cover slips in a few hundred hours. Hydraulic or cable actuation is a different cover family — do not order this mechanical cover because the diameter matched.
SRC-CL-RB28 is the 28 mm-bore release bearing for that same pack. It is cheap next to a second split. A fork with elongated holes will not centre it. Incomplete release burns a new plate as surely as a wrong facing. Order the bearing with the disc and cover, not after the tractor is already apart.
Disc versus cover versus bearing
- Lining worn, glazed or oil-soaked: disc (SRC-CL-D330), then inspect flywheel and cover height
- Pedal high, clamp lost, fingers worn: cover (SRC-CL-C330), not a thicker disc
- Noise on the fork, seized race, incomplete release: bearing (SRC-CL-RB28) plus fork check
- Unknown which failed: quote the three as a pack; do not guess from a cover photo
When they must travel together
A glazed flywheel will destroy a new organic plate. A cover that has lost height will not be saved by a thicker disc. A bearing that drags will burn the facing you just fitted. The 6120M fitment on these three SKUs is a shortlist, not a substitute for spline, lining OD and cover tag. If the serial uses a dual-plate or PTO pack, none of these three is the line.
What a photograph will not tell you
A cover photograph shows springs, maybe a logo, and the colour of the paint. It does not show spline count, lining outside diameter, whether the damper springs are collapsed, or whether the flywheel is glazed. A disc photograph does not confirm cover height or actuation. A bearing photograph does not confirm fork wear. Send the stamp and the measurements; use the photo as context, not as the specification. If the only number you have is '330 mm', you still have not named a SKU — that diameter is shared across travel packs that are not this 6120M trio.
Workshops that order from a phone picture typically get the disc right by luck and the cover or bearing wrong. The callback is the second split, not a polite email. If the tractor is already apart, measure the spline and lining OD before the parts van leaves. If it is still together, copy the hub and cover tags from the last invoice or the parts book for that serial.
Typical mixed-up orders
Ordering only SRC-CL-D330 because the lining was to the rivets, then discovering the cover has lost height, is the common pattern. Ordering only SRC-CL-C330 because the pedal felt high, then finding oil on the facing, is the same pattern from the other end. Ordering SRC-CL-RB28 after the tractor is together again because the new plate started to drag is how a cheap bearing becomes an expensive revisit. Quote the three as a pack when the failure mode is unclear; drop a line only when that piece is measured serviceable.
Do not substitute a dual-plate or PTO disc because the tractor has a PTO. Travel and PTO are different packs. Do not order a ceramic facing because the last organic plate glazed — first ask whether oil, a tired cover or loader shuttle duty caused the glaze. Organic on D330 is the listed facing for mixed field and road work on this 6120M shortlist.
Organic facing suits mixed fieldwork and road work. Loader reverse-shuttle duty that glazed the last plate in a season needs a different facing, not a cheaper copy of D330. Keep grease off the linings; lightly lubricate the spline only. Confirm OEM-CL-D330 / AL156330 on the hub, OEM-CL-C330 / AL156331 on the cover, OEM-CL-RB28 on the bearing.
How to write the first email
Send spline count and major diameter, lining OD, cover or OEM tag, single versus dual plate, facing, actuation (mechanical on this pack), make, model, and whether this is travel or PTO. If you already know which of the three failed, name that SKU and still confirm the other two are serviceable. SEROC quotes B2B; listed SKUs are available to quote. No webshop checkout.
The clutch pillar walks the measurement order. Identification, failure symptoms and installation mistakes sit next to this comparison so a 'bad clutch' complaint becomes a named part. Open the three product pages before you send a photo of the cover springs.
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