Description
YLD7 YLD Type Flanged Coupling – 28–110mm Bore Rigid Bolted-Flange Shaft Connector to GB5843-86
The YLD7 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 120 mm outer diameter, 28–110 mm bore range, and nominal torque rating of 160 N·m, the YLD7 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 4800 rpm for cast iron hubs and 7600 rpm for cast steel hubs. Overall length including spacer: 458 mm (spacer length L0 = 168 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 YLD7 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 | YLD7 |
| Type | YLD Type Flanged Coupling with Alignment Tenon |
| Standard | GB 5843-86 |
| Bore Range (d) | 28–110 mm |
| Outer Diameter (D) | 120 mm |
| Flange Diameter (D1) | 95 mm |
| Overall Length (L) | 458 mm |
| Spacer / Face Distance (L0) | 168 mm |
| Flange Bolts | 4×M10 |
| Nominal Torque (Tn) | 160 N·m |
| Max Speed – Cast Iron | 4800 rpm |
| Max Speed – Cast Steel | 7600 rpm |
| Rotational Inertia | 0.044 kg·m² |
| Mass | 8.8 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 (4800 rpm) or cast steel (7600 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
- API process pump drive couplings — spacer body provides standard ASME/API seal access clearance
- Oil and gas pump drive connections — offshore and onshore process pump seal access coupling
- Large centrifugal pump motor connections — spacer coupling for seal replacement without pump downtime
- Mining process pump drive connections — slurry pump seal access via spacer coupling
For custom bore configurations and volume supply, contact our technical team.
Customer Reviews and Case Studies
★★★★★
United Kingdom — Large Pump OEM
YLD7 spacer couplings are standard on our large API process pump range. At 160 N·m and 458 mm spacer length, the coupling covers our 30–75 kW pump class. The alignment tenon and precision bore maintain our shaft concentricity specification on every reassembly.
— Chief Product Engineer, Birmingham
★★★★★
United States — Chemical Plant Operations
We use YLD7 on our largest single-stage centrifugal pump drives. The spacer body allows our API pump seal maintenance procedure to be executed without motor disconnection, reducing our planned maintenance duration significantly.
— Process Engineer, Baton Rouge
★★★★☆
China — Large Pump Manufacturing
Specified for our export pump range where API-type spacer couplings are standard customer specification. The YLD7 meets dimensional and performance requirements and the alignment tenon simplifies our end-user maintenance documentation.
— Engineering Manager, Shanghai
Frequently Asked Questions
What alignment is required before installing a YL flanged coupling?
Both shaft ends must be accurately aligned before connecting the YL coupling. Recommended alignment tolerances are: parallel offset ≤ 0.03–0.05 mm; angular deviation ≤ 0.05 mm/m. These are tighter than flexible coupling requirements. Use a dial indicator or laser alignment tool. For YLD type, the alignment tenon provides centring on reconnection, but initial installation alignment is still required.
What torque should the YL coupling flange bolts be tightened to?
Tightening torque varies by bolt size: M6 approximately 10 N·m; M8 approximately 25 N·m; M10 approximately 50 N·m. Use a calibrated torque wrench and tighten bolts in a cross-pattern sequence. Reamed-hole (precision fit) bolts should be lightly oiled before insertion to prevent galling during tightening.
Can the YL/YLD coupling accommodate different bore sizes on each hub?
Yes. The two hub halves can be machined to different bore diameters, provided each bore falls within the model’s specified bore range. Specify d1 and d2 independently when placing your order.
What is the rated torque basis for YL/YLD flanged coupling?
The nominal torque Tn is the design torque for continuous operation. The coupling is sized based on the shear stress in the coupling bolts and the keyway bearing stress. For applications with shock or cyclic loading, apply a service factor (1.5 for smooth loads, 2.0–2.5 for shock loads) to the application torque before comparing with Tn.
Does the YLD spacer body add significant rotational inertia?
The spacer tube contributes additional rotational inertia compared to the standard YL type. For motor sizing and drive system dynamics calculations, the YLD’s additional inertia should be calculated using J = (m × r²)/2 for a thin-walled cylinder approximation and added to the total reflected inertia at the motor shaft.
Source the YLD7 YLD Flanged Coupling
Ever Power manufactures the YLD7 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.