Universal joint

01

Rate torque at your working angle and speed

HPC's industrial universal joint catalogue gives torques for a 10° working angle and tells buyers to apply an angle factor: 1.25 at 5°, 1.00 at 10°, 0.75 at 20°, 0.45 at 30° and 0.30 at 40°. Its worked example divides 100 Nm to be transmitted at 20° by 0.75 and selects a joint able to carry 133 Nm at the required speed. [1]

Rated torque also falls with speed. For HPC's single needle-roller joint H5-A-25/25 (50 mm outside diameter, 25 mm bore) the catalogue lists 240 Nm at 250 rpm, 156 Nm at 1000 rpm and 102 Nm at 4000 rpm; its plain-bush DIN 808 joints are limited to 800 rpm. [1]

Lovejoy's needle-bearing joint data (shown on Timken's product pages) list a static breaking torque of 2,500 in·lb for size NB8 and warn that static breaking torque is not a recommended operating torque. [2]

Editorial calculation: to transmit 50 Nm at 30° and 2000 rpm, divide by HPC's 0.45 factor to get about 111 Nm, so the H5-A-25/25 (132 Nm at 2000 rpm) would be the smallest listed size meeting that figure. [1]

Give the supplier the continuous and peak torque, speed range, working angle of each joint, shaft bores and connection (keyway, spline, square, hex), overall length, single or double joint, duty cycle and shock, environment (dirt, water, temperature), lubrication or boot requirement, and quantities.

02

Choose single or double joint and bearing type

Lovejoy states that the maximum operating angle for power transmission is 25° for its needle-bearing joints, rated to 6000 rpm and −30 to 212 °F, and recommends a double universal joint (two joints back to back joined by a short shaft) for greater angles. It notes that lubrication is required for optimal wear and that boots and lubricant extend joint life. [2]

HPC's needle-roller joints, with C45 steel bodies and hardened 18NCD4 steel pins, are listed for speeds up to 4000 rpm and misalignment up to 45°, while its smooth hardened-bush DIN 808 joints are for up to 800 rpm; the economy series is aimed at low speeds and loads such as valve control. [1]

Editorial calculation: a single cross joint does not turn at constant speed; by the standard Hooke's joint relation the output speed swings between cos β and 1/cos β times the input twice per revolution, about ±1.5% at 10° and ±6% at 20° (cos 20° ≈ 0.940). Ask how the supplier phases and aligns joints in a two-joint shaft to cancel this.

Vehicle driveshafts run far smaller angles than industrial joints. Dana's Spicer driveline operating-angle guidance says joint angles at each end of a driveshaft should be at least half a degree and equal within one degree (half a degree for motor homes and shafts ahead of transfer cases), and that for vibration-free running they should not exceed three degrees; any angle above three degrees lowers joint life and may cause vibration. Its maximum recommended angles fall with shaft speed: 3.2° at 5,000 rpm, 4.2° at 4,000 rpm, 5.8° at 3,000 rpm, 8.7° at 2,000 rpm and 11.5° at 1,500 rpm. [3]

Editorial calculation: at 3,000 rpm Spicer's 5.8° limit sits far below the 25° and 45° maximum angles quoted for industrial joints above; the speed fluctuation from a single joint at 5.8° is about ±0.5% (1 ÷ cos 5.8° ≈ 1.005), against about ±10% at 25°, which is why high-speed vehicle shafts keep angles small and matched at both ends. [3]

A third maker's DIN 808 range shows the plain-bearing alternative. ELBE lists its 0.700 series universal joint shafts to DIN 808 with maximum torque from 6 to 450 Nm, hub bores of 10–40 mm, speeds up to 1,000 rpm, deflection angles up to 45° and lengths of 34–4,000 mm, in single or double form with or without length extension, with a plain (sliding-block) bearing that needs lubrication, optional bellows, and bores plain, keyed to DIN 6885, square or hexagon; materials include standard, stainless and high-strength steels and aluminium. [4] Editorial calculation: ELBE's 1,000 rpm limit for plain-bearing joints is a quarter of the 4,000 rpm HPC lists for needle-roller joints and a sixth of Lovejoy's 6,000 rpm, so plain-bearing DIN 808 joints suit slower drives and the needle-bearing types higher speeds. [4] [1] [2]

03

Compare what suppliers offer

Suppliers linked to this page list universal joints; each card links to the page reviewed.

Listings include automotive universal joints, forklift steering-column joints, tractor and gearbox universal joints, universal joint couplings and forged or cast joint parts.

04

Trace the joint components

This is a functional reference built from the sources cited; it is not one maker's design.

05

Fill the specification fields with values for your shaft

A universal joint quotation needs values for your shaft. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.

06

Send the torque, angle and speed data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Torque: [continuous; peak; shock]
Angle: [per joint; single or double]
Speed: [rpm range]
Shafts: [bores; connection; length]
Environment: [dirt; water; temperature]
Supply: [lubrication; boot; quantity]

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