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Brand: Lovejoy
Lovejoy HercuFlex FX 4 Flanged Gear Coupling
Description
Lovejoy FX 4 is size 4 of the HercuFlex FX Series flange-style gear coupling, rated 311,540 in-lb (35,199 Nm) nominal and bored to 5.875 in (149 mm). It keeps the standard AGMA flange interface so it can be fitted where a flanged gear coupling already sits, while Lovejoy’s finite-element redesign raises torque and bore capacity for the same envelope.
A redesigned flanged gear coupling on the AGMA flange interface
HercuFlex gear couplings are aimed at heavy drives where torque density and reliability matter, and the catalogue service-factor chart names the machines concerned: crushers, mills, cranes and hoists, conveyors, paper machines, compressors and large pumps. The catalogue lists best-in-class bore and torque capacity, 1.5 degrees of misalignment per gear mesh, improved fastener corrosion resistance and an advanced seal design with superior contamination resistance. The FX is the usual starting point, alongside the CX continuous-sleeve type, the FXL labyrinth-seal flanged type and the RA and RAHS rigid adjustable couplings.
Because the coupling has two gear meshes, each flexing independently, it accommodates angular offset at both hubs and the offset between shafts increases with the distance between meshes. Hubs can be arranged normally, with one hub reversed, or with both hubs reversed to vary the overall length.
Technical specifications
| Parameter | Specification |
|---|---|
| Size | FX 4 |
| Nominal torque | 311,540 in-lb (35,199 Nm) |
| Maximum bore | 5.875 in (149 mm) |
| Maximum speed, unbalanced / balanced | 3,000 RPM / 4,500 RPM |
| Misalignment | 1.5 degrees per gear mesh |
| Overall length, normal hubs (OAL) | 9.75 in (247.7 mm) |
| OAL, one hub reversed (OAL1) | 10.44 in (265.2 mm) |
| OAL, two hubs reversed (OAL2) | 11.13 in (282.7 mm) |
| Hub length through bore (LTB) | 4.75 in (120.7 mm) |
| Shaft separation (BSE) | 0.25 in (6.4 mm) |
| Hub diameter (HD) | 8.10 in (205.7 mm) |
| Sleeve diameter (D) | 9.83 in (249.8 mm) |
| Flange diameter (FD) | 12.50 in (317.5 mm) |
| Dimension TS | 5.69 in (144.5 mm) |
| Exposed bolts | 8 off, 3/4-16, 11.000 in bolt circle |
| Shrouded bolts | 14 off, 5/8-18, 10.625 in bolt circle |
FX Series sizes
| Size | Nominal torque | Maximum bore | RPM unbalanced / balanced |
|---|---|---|---|
| 1 | 11,300 in-lb (1,277 Nm) | 1.875 in (48 mm) | 6,000 / 9,000 |
| 1.5 | 26,100 in-lb (2,949 Nm) | 2.438 in (62 mm) | 5,500 / 8,250 |
| 2 | 44,850 in-lb (5,067 Nm) | 3.063 in (78 mm) | 5,000 / 7,500 |
| 2.5 | 79,700 in-lb (9,005 Nm) | 3.625 in (92 mm) | 4,400 / 6,600 |
| 3 | 135,700 in-lb (15,332 Nm) | 4.250 in (108 mm) | 4,000 / 6,000 |
| 3.5 | 203,550 in-lb (22,998 Nm) | 5.000 in (127 mm) | 3,500 / 5,250 |
| 4 | 311,540 in-lb (35,199 Nm) | 5.875 in (149 mm) | 3,000 / 4,500 |
| 4.5 | 427,460 in-lb (48,296 Nm) | 6.750 in (171 mm) | 2,700 / 4,050 |
| 5 | 584,890 in-lb (66,084 Nm) | 7.750 in (197 mm) | 2,500 / 3,750 |
| 5.5 | 771,300 in-lb (87,145 Nm) | 8.625 in (220 mm) | 2,200 / 3,300 |
| 6 | 1,207,500 in-lb (136,429 Nm) | 9.500 in (241 mm) | 2,100 / 3,150 |
| 7 | 1,638,750 in-lb (185,154 Nm) | 11.250 in (287 mm) | 2,000 / 3,000 |
Selecting and lubricating the FX 4
Multiply application torque, HP x 63,025 / RPM, by the application service factor and compare with the nominal torque column; then check the bore and the speed limit and any special needs such as spacer or floating-shaft BSE, shear-pin torque or mill-motor tapers. Service factors in the catalogue run from 1.0 for centrifugal pumps, blowers and compressors, through 2.0 for hammer mills and reciprocating pumps, to 3.0 for crushers; add 1.0 for drives with internal combustion engines.
Gear couplings need grease. Lovejoy Gear Coupling Grease is NLGI 0/1, lithium soap and polymer thickened, with a dropping point of 320 F (160 C), a usable range from below -20 F (-29 C) to 250 F (121 C) continuous and 325 F (163 C) short exposure, supplied in 14 oz cartridges, 1 lb and 5 lb cans.
Installation and operation notes
The sleeve bolts are offered as exposed or shrouded; the catalogue sleeve table lists, for size 4, a sleeve length of 4.25 in, 8 exposed bolts of 3/4-16 or 14 shrouded bolts of 5/8-18, and a minimum and maximum bolt grip for each. Follow the catalogue warnings, do not exceed ratings, align within the stated misalignment, and recheck alignment if the coupling vibrates or beats. Puller bolt holes are provided in the flex hub on sizes 2 and larger; for size 4 they are 5/8-11 holes, 0.94 in deep, on a 6.44 in bolt circle. Check coupling guards, seals and grease level at each maintenance stop.
Where it is used
Typical duties are high-torque, low-speed drives between a gearbox and a conveyor, mill or crusher, and between large motors and compressors. A heavy-duty alternative family on this site is the Flender ZAPEX ZW gear coupling; hubs are not interchangeable between makers unless the flange interface is confirmed.
Operating notes for Oman and the GCC
Flanged gear couplings are used on heavy drives such as crushers, mills, conveyors, cranes, compressors and large pumps in cement, mining, steel and oil and gas plants in the region. Gear couplings need the correct grease and regular lubrication, so the lubrication interval should be shortened for very hot or dusty duty, and seals should be inspected at each interval because sand in the gear mesh causes fast wear. When replacing an existing flanged gear coupling, the AGMA flange interface helps, but the bore, keyway and shaft separation should still be checked against the drive drawing.
Information to send with an enquiry
- Machine power, speed and the type of drive
- Shaft diameters, keyways and shaft separation
- Existing coupling make and size if replacing
- Any spacer, floating shaft or special seal requirement
- The grease currently used on site, so the lubrication plan can be checked
Frequently asked questions
What is the FX 4 gear coupling?
A flanged-sleeve gear coupling of the HercuFlex FX Series, rated 311,540 in-lb (35,199 Nm) nominal with a 149 mm (5.875 in) maximum bore.
How much misalignment does it accept?
The catalogue states 1.5 degrees of misalignment per gear mesh.
Is it interchangeable with other flanged gear couplings?
It uses the standard AGMA flange interface for field interchangeability, and the catalogue includes a flange interchangeability section.
Which lubricant is recommended?
Lovejoy Gear Coupling Grease, an NLGI 0/1 lithium soap and polymer grease with a 320 F dropping point, usable continuously to 250 F (121 C).
What speed limits apply?
Size 4 is rated to 3,000 RPM as supplied and 4,500 RPM when balanced, per the FX Series table.
Documents and quotation
The HercuFlex gear coupling catalogue (11170 Rev G) is hosted on this page. See Couplings and Shaft Locking Devices. Seven Star LLC is an independent supplier in Muscat; send size, bore sizes, BSE, speed and quantity for a quotation.
Datasheets & Documents
- Datasheet Lovejoy HercuFlex gear coupling catalogue 11170 Rev G Download
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About brand
Lovejoy is an American maker of industrial couplings and power transmission products, based in Downers Grove, Illinois. Thomas Lovejoy founded the company in Chicago in 1900 to make tooling for the railroad and steel industries; in 1927 it bought Louis Ricefield's patent for the jaw coupling, which became its core product. Timken acquired Lovejoy on 8 July 2016.
Lovejoy company profile
| Founded | 1900, Chicago, by Thomas Lovejoy |
|---|---|
| Headquarters | Downers Grove, Illinois |
| Ownership | The Timken Company, since July 2016 |
| Key product | Jaw coupling, patent bought in 1927 |
| Product families | L-type and CJ curved jaw couplings, jaw in-shear couplings, S-Flex and Quick Flex elastomeric couplings, SX disc couplings, grid and gear couplings, universal joints |
Milestones
- 1900: Thomas Lovejoy founds the company in Chicago.
- 1927: Lovejoy buys the jaw coupling patent.
- 1960s: Universal joints and variable speed pulleys are added.
- 2016: Timken acquires Lovejoy.
Couplings and universal joints from Lovejoy
The Lovejoy range includes jaw and jaw in-shear couplings, S-Flex and Quick Flex elastomeric couplings, curved jaw couplings, HercuFlex and high-speed gear couplings, disc couplings and grid couplings, together with Curtis block and pin universal joints.
Lovejoy products at Seven Star LLC
Seven Star LLC lists Lovejoy coupling families with catalogue data, torque ratings and bore tables so that engineers can match a coupling to a drive. Send the shaft sizes, torque, speed and misalignment for a quotation.
Lovejoy products we list
Facts checked against Lovejoy's own history page and Timken's 2016 SEC filings, October 2026.
Related products
Frequently Asked Questions
What is the FX 4 gear coupling?
A flanged-sleeve gear coupling of the HercuFlex FX Series, rated 311,540 in-lb (35,199 Nm) nominal with a 149 mm (5.875 in) maximum bore.
How much misalignment does it accept?
The catalogue states 1.5 degrees of misalignment per gear mesh.
Is it interchangeable with other flanged gear couplings?
It uses the standard AGMA flange interface for field interchangeability, and the catalogue includes a flange interchangeability section.
Which lubricant is recommended?
Lovejoy Gear Coupling Grease, an NLGI 0/1 lithium soap and polymer grease with a 320 F dropping point, usable continuously to 250 F (121 C).
What speed limits apply?
Size 4 is rated to 3,000 RPM as supplied and 4,500 RPM when balanced, per the FX Series table.
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