Description
YLD8 YLD Type Flanged Coupling – 32–140mm Bore Rigid Bolted-Flange Shaft Connector to GB5843-86
The YLD8 YLD type flanged coupling is a YLD type flanged coupling with alignment tenon and spacer body designed to connect two co-axial cylindrical shaft ends rigidly through a bolted flange joint, conforming to Chinese national standard GB5843-86. With a 130 mm outer diameter, 32–140 mm bore range, and nominal torque rating of 250 N·m, the YLD8 serves shaft connections in industrial drives where a rigid, zero-backlash connection is required combined with the ability to disconnect the two shaft ends by removing the flange bolts — without moving either shaft axially. Maximum speed rating is 4300 rpm for cast iron hubs and 7000 rpm for cast steel hubs. Overall length including spacer: 508 mm (spacer length L0 = 169 mm). The spacer body provides maintenance access clearance between the two hub faces.
The YL type flanged coupling consists of two identical hub halves, each machined with a bore and keyway to receive one shaft end, and each terminating in a precision-machined circular flange. The two flanges are bolted together with 4×M10 reamed-hole precision bolts that both clamp the faces together and transmit shear torque through the bolt shank. Torque is transmitted from each shaft into its hub through the key-keyway engagement, through the hub body to the flange face, and across the bolted joint to the opposing hub and shaft. The result is a rigid, zero-backlash connection that can be separated by removing the 4 flange bolts without disturbing shaft alignment — an advantage over sleeve couplings that require axial shaft movement for installation or removal. The YLD type’s precision alignment tenon on each flange face ensures that the two hub halves re-centre automatically when the bolts are tightened after maintenance reassembly, eliminating the need for dial indicator realignment.
The YLD8 conforms to GB5843-86, which specifies dimensions for flanged couplings for cylindrical shaft connections transmitting nominal torques from 10 to 20,000 N·m. Bore and keyway dimensions conform to GB3852-1997. The complete YL and YLD flanged coupling range is listed on our product catalog page.
Technical Specifications
| Parameter | Value |
|---|---|
| Model | YLD8 |
| Type | YLD Type Flanged Coupling with Alignment Tenon |
| Standard | GB 5843-86 |
| Bore Range (d) | 32–140 mm |
| Outer Diameter (D) | 130 mm |
| Flange Diameter (D1) | 105 mm |
| Overall Length (L) | 508 mm |
| Spacer / Face Distance (L0) | 169 mm |
| Flange Bolts | 4×M10 |
| Nominal Torque (Tn) | 250 N·m |
| Max Speed – Cast Iron | 4300 rpm |
| Max Speed – Cast Steel | 7000 rpm |
| Rotational Inertia | 0.064 kg·m² |
| Mass | 11.2 kg |
Structure Drawing
Dimension Reference
Rigid Zero-Backlash Connection
The bolted flange joint transmits torque rigidly with zero angular play. Every rotational increment on the driving shaft is replicated exactly on the driven shaft — essential for position feedback and phase-critical drive applications.
Disconnect Without Shaft Movement
Removing the flange bolts disconnects the two shaft ends without moving either shaft axially. This allows motor removal, driven equipment service, or shaft inspection without disturbing bearing housings or shaft alignment.
Cast Iron / Cast Steel Options
Hub material choice of cast iron (4300 rpm) or cast steel (7000 rpm) covers both standard industrial speed requirements and higher-speed applications. The torque rating is the same for both materials.
GB5843-86 Standard Compliance
Full conformance to national standard GB5843-86 ensures dimensional interchangeability with other GB-compliant couplings. Keyway dimensions per GB3852-1997 ensure compatibility with standard motor and driven equipment shaft keyways.
Manufacturing
Typical Applications
- Large API pump drive couplings — spacer length per API 610 seal access requirement
- Heavy industrial pump motor connections — spacer flanged coupling for large process pump seal service
- Water supply and treatment pump drives — spacer coupling for maintenance access in large pump stations
- Large industrial mixer drive connections — spacer coupling for agitator seal access in large reactor vessels
For custom bore configurations and volume supply, contact our technical team.
Customer Reviews and Case Studies
★★★★★
Germany — Large Industrial Pump OEM
The YLD8 is our top-of-range spacer coupling for large API and industrial pump connections. At 250 N·m and 508 mm spacer length, the coupling covers our 75–200 kW pump class. The alignment tenon maintains shaft concentricity through extended service intervals.
— Senior Engineer, Mannheim
★★★★★
Australia — Mining and Mineral Processing
Used on large slurry pump drive connections at our gold processing facility. The YLD8 spacer body allows seal replacement without disturbing motor alignment — reducing our maintenance window duration at each planned seal change.
— Rotating Equipment Manager, Perth
★★★★☆
Brazil — Large Pump Plant
Installed on large-scale water supply pump drives. The YLD8 has operated reliably through our continuous pumping schedule and the spacer design simplifies our seal maintenance procedure at this pump size.
— Maintenance Manager, Brasília
Frequently Asked Questions
What is the maximum speed difference between cast iron and cast steel versions?
The speed limit is based on peripheral velocity: 30 m/s for cast iron, 50 m/s for cast steel. For example, YL5 cast iron: 5,500 rpm; cast steel: 9,000 rpm. For applications operating above the cast iron speed limit, specify cast steel when ordering. The torque ratings are the same for both materials.
How is the YLD type spacer body connected between the two hub flanges?
The spacer tube is a machined cylindrical or flanged tube fixed between the two hub flange faces by the same bolt circle that connects the hubs. The alignment tenon on the spacer end faces locates concentrically with each hub. The spacer is a third component in addition to the two hubs — all three are bolted together to form the complete coupling assembly.
Are drawings and dimensional data available for YL/YLD couplings?
Yes. Dimensional drawings in PDF and DXF format are available on request for all YL and YLD models and bore configurations. Specify the model, bore sizes, and hub types (Y or J₁) when requesting drawings.
What is the application-level difference between YL and YLD type?
YL is specified when shaft maintenance does not require access to the coupling region and re-alignment on reconnection is acceptable. YLD is specified when: (1) shaft seals require access with the coupling in place; (2) the spacer body length matches a pump API seal access dimension; (3) the alignment tenon eliminates realignment time in high-frequency maintenance schedules.
Is the YL type coupling balanced as standard?
Standard YL and YLD couplings at smaller frame sizes rely on geometric symmetry for inherent balance. For high-speed applications approaching the maximum rated speed, dynamic balance correction can be provided. Specify the balance grade required (ISO 1940 G6.3 or G2.5) when enquiring.
Source the YLD8 YLD Flanged Coupling
Ever Power manufactures the YLD8 and the complete YL/YLD flanged coupling range to GB5843-86 direct from our factory. Specify bore sizes, hub type (Y or J₁), and material (cast iron or cast steel) for a prompt technical and commercial response.