A detachable hook-and-bar chain uses repeated links whose hook engages the transverse bar of the next link. The enlarged illustration shows a formed-steel version of this construction. It is distinct from roller chain joined by a separate spring-clip connecting link.
Detachable Link Chain Interactive Calculator
Watch three formed-steel hook-and-bar links articulate without changing pitch. Calculate net drive pull, mean shaft torque and speed from power, average chain speed, pitch and tooth count. The entered multiplier scales the design load; it is not a chain rating.
Equation Used
- Steady mean transmitted power and positive mean chain speed; no slip in pitch indexing.
- Mean chain advance is exactly Np per revolution. Instantaneous chordal speed and torque ripple are not calculated.
- Hook-and-bar profiles are schematic; pitch is geometric, not a dimensional specification for a catalog chain.
- The visual articulation is slowed and separate from shaft rpm. It illustrates a turn of 360°/N, not a verified mechanical articulation limit.
Average chain speed uses N pitches per sprocket revolution, not the circumference of the pitch circle. Mean torque follows work per revolution. Net pull is tight-side minus slack-side tension, not total tight-side tension.
A repeated hook-and-bar joint
Each illustrated link has two side rails, a transverse bar and a rolled hook. The next link’s hook surrounds that bar to form an articulating joint. The animation keeps the distance between successive joint centres constant while the outer links bend relative to the middle one.
The maximum illustrated bend is 360° divided by the selected sprocket tooth count: the change of direction between successive sides of an ideal pitch polygon. It is an educational geometry comparison, not a collision or maximum-angle certification for a real chain.
The illustration follows the formed-steel construction shown in the manufacturer reference. Cast detachable chain is a related construction, but the material and exact hook profile depend on the chain series. This view does not show an assembly or uncoupling procedure.
Use the chain series and drive geometry together
Detachable hook-and-bar chains are used in material-handling and agricultural equipment. Selection requires the actual manufacturer’s pitch, sprocket compatibility, operating load and service guidance. The picture is not a product drawing.
Direction guidance is also product-specific. For its JK pattern steel chain, John King describes operation in either direction and gives wear-related guidance for hook orientation, including an exception for fine abrasive material. It would be incorrect to claim that every detachable chain can carry load in only one travel direction.
Power, net pull and pitch advance
One mechanical horsepower equals 33,000 ft·lbf/min. With mean chain speed v in ft/min, net pull is 33,000 HP/v. The entered design multiplier K scales that value for the displayed factored calculation.
A sprocket with N teeth advances N chain pitches in one revolution. For pitch p in inches, mean rpm is 12v/(Np). Work per revolution is F Np in inch-pounds, so factored mean torque is F Np/(2Ï€). These equations satisfy the same mean power balance.
The pitch-circle diameter is p/sin(π/N). Its circumference is greater than the perimeter Np of the pitch polygon. Using πD as the chain travel per revolution would introduce an error, especially with few teeth. The pitch diameter is therefore shown separately rather than used in the mean-speed equation.
A 3.6-hp drive at 200 ft/min
With multiplier K = 1, net pull is 33,000 × 3.6/200 = 594 lbf. For a 12-tooth sprocket and 2.308-inch pitch, one revolution advances 27.696 inches. Mean speed is therefore about 86.66 rpm and mean torque about 2,618.3 in·lbf. The geometric pitch-circle diameter is about 8.917 inches.
Doubling the multiplier doubles the factored pull and torque but leaves rpm and diameter unchanged. Increasing chain speed at constant power reduces net pull; it does not establish whether the selected chain is suitable at that speed.
Mean drive values are not a complete selection
The calculation gives net power-transmitting pull, not the total tension in the tight strand. Slack-side tension, pretension, weight, acceleration and other loads may need separate treatment.
Instantaneous speed varies as a chain engages a sprocket’s discrete pitch polygon. The calculator reports mean speed and mean torque; it does not calculate that ripple or its dynamic loading. Manufacturer operating limits, lubrication and wear guidance remain specific to the selected series.
Detachable-chain questions
Does the calculator give a maximum operating speed?
No. The calculator gives mean shaft speed and geometric pitch diameter. The allowable operating speed depends on the selected chain, sprockets, lubrication and application loads.
Why is rpm based on Np?
Each tooth indexes one pitch, so a full revolution advances N pitches. A chain follows discrete joints, not the circumference of a smooth pulley.
Why is mean torque not exactly pull times pitch radius?
Pitch-radius multiplication is a geometric approximation. The mean value used here comes from work over one full revolution and remains consistent with the entered power and average speed.
Does the animation run at shaft speed?
No. It is a slowed joint-articulation demonstration. The calculated mean shaft speed is displayed separately.
Can I use the drawing to manufacture a link?
No. Hook profile, clearances, material and allowable loads are not specified by this schematic.
References
John King Chains, JK Pattern Steel Detachable Chains, formed-steel hook-and-bar construction, pitch data and direction guidance. Renold Conveyor Chain Designer Guide, pitch-polygon geometry and chain-speed variation.
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