Gears & PinionsInternal gears
Heavy-Duty Planetary Internal Ring Gear Assembly
Cast internal ring gear assembly in 42CrMo or ZG35CrMo with hardened involute teeth, an integrated bearing bore and anti-rotation lugs for planetary drives.
Internal Tooth Machining and Hardening
Internal teeth are cut by gear shaping and finished by profile grinding so the ring meshes with the sun gear and planet gears as one complete gear set. Tooth forms cover straight, helical, herringbone and internal teeth; the largest outside diameter we machine is Ø8,000 mm and the largest module is M60.
Tooth surfaces are induction hardened after machining, with quenching available up to Ø8,000 mm diameter. Pitch, runout and hardness are measured on every ring before it leaves the floor.
Structure and Locating Features
The ring gear, bearing seat and mounting flange form a single cast body. The central bearing bore takes the support bearing directly and locates the planet carrier or output shaft, so a separate housing is no longer needed and the axial length of the transmission is shortened.
Radial lugs on the lower face drop into matching slots in the equipment housing and stop the ring from turning under reaction torque. Bolts through the top flange lock it axially and carry the end seal. Assemblies of this type are commonly used in planetary reducers, swing drives, travel drives, mine hoists and metallurgical tilting mechanisms.
Materials and Heat Treatment
Standard grades are 42CrMo and ZG35CrMo, and blanks can be castings, forgings or rolled rings depending on size and quantity. Normalizing and quenching and tempering are carried out in-house to raise strength and impact toughness before tooth cutting.
Inspection, Customization and Delivery
Pitch, runout, hardness and ultrasonic testing are all done in-house, with dimensional, form and position, UT and MT reports supplied on request. Typical lead time is 8–12 weeks after drawing release.
Module, number of teeth, accuracy grade, bore diameter and lug positions are machined to the customer's drawing, and the tooth profile is matched to the mating sun and planet gears.
Specifications
- Material
- 42CrMo / ZG35CrMo
- Blank type
- Alloy steel casting (forging or rolled ring optional)
- Heat treatment
- Normalizing + quenching and tempering; tooth surface induction hardening
- Tooth profile
- Involute internal spur gear (straight teeth)
Common questions
- Can you machine this part to my drawing?
- Yes. Every part is quoted from the drawing. Send a PDF, DWG, DXF, STEP or IGES file with the material, quantity and any inspection requirements, and we reply within one working day.
- How are the material and heat treatment decided?
- They follow your drawing. The specification table shows the range normally used for this part type; the final material and heat treatment are confirmed with the quotation.
- What lead time and inspection come with the part?
- Lead time is set in the quotation and depends on material, size, quantity and inspection scope. Material verification, in-process checks and final inspection records are archived with the part, and any extra certification is agreed before production.
- How is the part packed for export?
- Export parts are rust-proofed and packed for the transport method and destination confirmed in the quotation, with lifting points and markings agreed before dispatch.
Every part is quoted from the drawing itself, not from a size band. Send it over and we answer with the process, the lead time and the tolerance we can hold.
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