A CYCLO gearbox uses an eccentric cycloidal disc drive instead of conventional gear teeth to set the bowl-to-scroll differential speed on a decanter centrifuge. Sentrimax services CYCLO-brand gearboxes, including Sumitomo units, by inspecting the cycloidal discs and pins for wear, machining or replacing worn components, and re-balancing the rebuilt assembly to ISO G 0.5.
What makes a CYCLO gearbox different
Most reduction gearboxes use involute gear teeth meshing directly against each other.
A CYCLO gearbox instead uses a cycloidal disc — a specially profiled rotating disc driven
by an eccentric input shaft — that engages a ring of pins around the housing. As the
eccentric drives the disc, the disc’s profile causes it to roll against the pins rather
than mesh tooth-to-tooth, producing the output rotation and, on a decanter, the
differential speed between bowl and scroll. This is a fundamentally different load path
than a planetary gear set, and it wears differently as a result.
Why cycloidal drives show up on decanters
Cycloidal gearboxes are used where a high reduction ratio is needed in a compact
housing, and where tolerance for shock loading matters. Because the load in a cycloidal
drive is distributed across multiple pins engaging the disc profile simultaneously,
rather than concentrated at a single pair of meshing teeth, this design handles the
torque reversals and momentary overloads that occur during centrifuge start-up, upset
conditions, and process disturbances differently than conventional gearing does.
What a CYCLO gearbox service involves
Servicing a cycloidal drive follows the same disciplined process as any other gearbox
at Sentrimax, but the inspection points are specific to this mechanism:
- Cycloidal disc inspection
- Checked for wear on the profile surface that engages the ring pins, and for any
scoring or pitting from contamination or lubrication breakdown. - Ring pin and pin housing inspection
- Each pin and its bore is checked for wear, since uneven pin wear changes how load is
distributed around the disc. - Eccentric shaft and bearing inspection
- The input eccentric and its bearings carry the drive load and are inspected alongside
the output bearings supporting the disc assembly. - Reassembly and balance
- Once repaired, the gearbox is reassembled with the rotating assembly, dynamically
balanced to ISO G 0.5, and put through a test run as part of the overall centrifuge
commissioning.
Rolling contact vs sliding contact: why it matters
Conventional involute gear teeth transmit load through a combination of rolling and
sliding contact at the point where two teeth meet, which is part of why lubrication
film condition matters so much to gear tooth life. A cycloidal drive’s disc-and-pin
engagement is predominantly a rolling contact rather than a sliding one across most of
its load path. That changes both the wear pattern an inspection looks for and the
lubrication demands of the unit — a CYCLO gearbox does not necessarily fail the same way
a worn planetary gear set does, even though the symptoms an operator notices (noise,
heat, backlash) can look similar from the outside.
Lubrication and oil sampling on CYCLO units
Because much of the internal wear on a cycloidal drive shows up first as changes in
lubricant condition rather than obvious visual damage, an oil sample sent for
third-party analysis at the inspection stage is a meaningful early indicator on these
units. Particle content and type can point toward disc or pin wear before it has
progressed far enough to be visible without disassembly.
Precision machining for cycloidal components
Where a cycloidal disc or eccentric shaft is salvageable rather than requiring
replacement, Sentrimax’s machine shop capability — milling, lathe-turning and
precision-grinding — is used to bring the component’s critical surfaces back to
tolerance. Where an exact replacement part is not available, the same engineering
services capability can design and manufacture a reverse-engineered replacement rather
than leaving the gearbox without a repair path.
Sumitomo and other CYCLO-brand units
Sentrimax stocks and services CYCLO-brand gearboxes, including Sumitomo CYCLO units, as
part of its centrifuge gearbox repair capability. Sentrimax is an independent MRO
provider, not affiliated with, authorized by, or endorsed by Sumitomo or any other
gearbox manufacturer — brand names here describe the equipment we service, nothing more.
Documentation delivered with a CYCLO gearbox service
As with any other gearbox type, a CYCLO service comes with the same documentation
trail as the rest of a Sentrimax repair: an inspection report identifying which
components — disc, pins, eccentric shaft, bearings or seals — were found worn and to
what extent, a quotation package covering the approved scope, a post-repair quality
control inspection, and a test run performance report confirming the reassembled unit
runs correctly. That documentation is what lets a maintenance manager verify what was
actually done to a mechanism that is otherwise difficult to inspect visually once it is
back in the housing.
What determines whether a CYCLO unit is rebuilt or replaced
As with planetary gearboxes, the rebuild-or-replace decision on a cycloidal drive is
made component by component: the disc, the pins, the eccentric shaft, the bearings and
the housing are each assessed individually during inspection. A housing in sound
condition paired with a worn disc and pin set is a very different scope of work than
housing damage that cannot be corrected by machining, and the two are not treated the
same simply because both are labeled a “CYCLO gearbox problem.”
Why identifying the drive type early avoids wasted diagnostic time
Because a cycloidal drive’s internal wear pattern differs from a planetary gear set’s,
diagnosing a CYCLO gearbox as if it were conventional gearing can lead to the wrong
components being checked first. Confirming the gearbox type — from a nameplate, original
documentation, or a quick inspection — before pursuing an in-depth diagnosis saves time
that would otherwise go toward ruling out the wrong failure mode.
Common CYCLO failure modes
- Disc profile wear. The cycloidal disc’s engagement surface wears
gradually with normal operation and more quickly if lubrication has degraded or
contamination has entered the housing. - Ring pin and roller wear. Individual pins or their rollers can wear
unevenly, changing how load is shared around the disc and accelerating wear at the
pins carrying more than their share. - Eccentric bearing wear. The bearings supporting the eccentric input
shaft carry the full drive load and are a common source of the backlash and noise
symptoms covered on our gearbox failure signs page. - Seal failure. As with any gearbox, a failed input or output seal
allows contamination in and lubricant out, and is often what turns a slow wear process
into a faster one.
How a CYCLO gearbox compares to conventional gearing in service
A conventional helical or worm gear reducer concentrates load at the meshing tooth
surfaces, which is where wear and eventual failure typically originate. A cycloidal
drive distributes load across the disc profile and multiple ring pins simultaneously,
which tends to give it a different service life profile under shock loading — the kind
of momentary overload a decanter can see during start-up or an upset in feed
conditions — compared to conventional gearing carrying the same average torque. This is
a design trade-off, not a guarantee that a CYCLO unit will outlast or underperform a
planetary gearbox in a given application; the right comparison depends on the specific
duty the centrifuge sees.
If your gearbox isn’t a CYCLO design
Not every decanter uses a cycloidal drive. If your centrifuge is showing the symptoms
covered on our gearbox failure warning
signs page but turns out to use a conventional gear train, see our
planetary gearbox rebuild page instead. If it
uses a hydraulic motor rather than any mechanical gear set to set differential speed, see
our hydraulic backdrive service page. For the
full range of gearbox repair options, see the
centrifuge gearbox repair overview.
What to expect if the disc or pins need replacement rather than machining
When wear on the cycloidal disc or ring pins has progressed beyond what
Le meulage de précision permet de corriger les défauts, les composants de remplacement sont approvisionnés ou, lorsqu'une précision exacte est requise, les pièces sont fournies.
match n'est pas disponible, fabriqué par les services d'ingénierie de Sentrimax et
atelier d'usinage. Les deux chemins mènent à la même séquence de réassemblage, d'équilibrage et d'essai.
comme une réparation qui ne nécessitait qu'un usinage — la documentation ne fait que mentionner les pièces
Des pièces remplacées plutôt que restaurées.
Voici à quoi ressemble le service CYCLO lorsqu'il est combiné à d'autres réparations
Il est rare qu'une boîte de vitesses CYCLO soit le seul élément nécessitant une intervention. Il est fréquent qu'une
l'entretien de la boîte de vitesses doit être combiné avec la réparation du bol ou de la spirale, le remplacement des roulements, ou
Les travaux d'étanchéité peuvent être effectués lors de la même visite, car tous ces composants partagent le même axe de rotation.
Dans ce cas, les travaux sur la boîte de vitesses sont effectués en même temps que le reste de l'assemblage.
réparer de sorte que l'équilibrage final et l'essai reflètent l'ensemble complet et réassemblé
la machine plutôt que la boîte de vitesses prise isolément.
Que faut-il avoir sous la main avant de nous contacter ?
Une photo de la plaque signalétique de la boîte de vitesses, la marque et le modèle de la centrifugeuse, et une description de ce qui
vous avez observé — bruit, chaleur, jeu, état de l'huile ou comportement du système de transport — sont
suffisamment pour entamer une conversation constructive sur la portée. Si la plaque signalétique est manquante ou
L'illisibilité ne constitue pas un obstacle ; il s'agit simplement d'une vérification effectuée par nos techniciens lors de l'intervention.
l'inspection initiale, parmi tout le reste.
Renseignez-vous sur l'entretien des boîtes de vitesses CYCLO
Si vous possédez une carafe ou un tricanter équipé d'un système CYCLO présentant des signes d'usure, un
L'inspection à réception confirme l'état du disque et des broches avant toute intervention.
cité.
Foire aux questions
En quoi l'usure d'une boîte de vitesses CYLO diffère-t-elle de celle d'une boîte de vitesses planétaire ?
Un engrenage cycloïdal répartit la charge sur le profil du disque et plusieurs axes annulaires, au lieu de la concentrer sur l'engrènement des dents. L'usure se manifeste généralement par une usure du profil du disque et une usure irrégulière des axes, contrairement aux piqûres observées sur les engrenages conventionnels ; l'inspection porte donc sur différentes surfaces.
Sentrimax est-il un centre de service agréé Sumitomo ?
Non. Sentrimax est un prestataire indépendant de services de maintenance, de réparation et d'exploitation (MRO) pour centrifugeuses. Nous assurons la maintenance des réducteurs Sumitomo CYCLO et d'autres marques dans le cadre de nos services de réparation de réducteurs, mais nous ne sommes ni affiliés à, ni autorisés par, ni approuvés par Sumitomo ou tout autre fabricant.
Une boîte de vitesses CYCLO peut-elle être réparée ou doit-elle être entièrement remplacée ?
Dans la plupart des cas, il est possible de le remettre en état. Le disque cycloïdal, les axes annulaires, l'arbre excentrique et les roulements sont inspectés individuellement, et seuls les composants usés au-delà des tolérances acceptables sont remplacés. Le remplacement complet n'est recommandé que lorsque les dommages ou l'usure du carter ne peuvent être corrigés par usinage.
L'entretien d'un réducteur CYCLO affecte-t-il le réglage de la vitesse différentielle de la centrifugeuse ?
Une reconstruction correctement effectuée rétablit le rapport de vitesse différentielle d'origine, car la géométrie du disque et de l'axe qui le produit est inspectée et réparée conformément aux spécifications. Tout écart est identifié et corrigé avant le remontage et l'équilibrage de la boîte de vitesses.
Que dois-je vérifier avant de supposer que ma boîte de vitesses est de type CYCLO ?
La plaque signalétique de la boîte de vitesses ou la documentation d'origine indiquent généralement sa marque et son modèle. Si ces informations sont indisponibles, nos techniciens vérifient le type de boîte de vitesses lors de l'inspection initiale, car la structure interne d'une transmission cycloïdale est visiblement différente de celle d'un engrenage planétaire.
Parlez à un spécialiste des centrifugeuses
Envoyez-nous les détails de la machine et nous vous ferons parvenir un devis et une description du périmètre d'inspection.
Renseignez-vous sur l'entretien des boîtes de vitesses CYCLO