§ 16
How large a force and what torque does a type 24 cylinder give at 6 bar?
Answer: An air brake cylinder's type (9, 12, 16, 20, 24, 30, 36) is its effective diaphragm area in square inches. Air pressure times area gives the force on the rod, and times the brake arm's (slack adjuster's) length gives the moment that rotates the brake cam or operates the disc brake's arm. The calculator is used when you compare axles, choose cylinder on replacement or want to explain why too long a stroke length gives poor braking. It does not replace a brake test.
Membranareal (cm²) = cylindertype (in²) × 6,4516, fordi 1 in² = 6,4516 cm²
Kraft F (N) = tryk (bar) × 10 × areal (cm²), fordi 1 bar = 10 N/cm²
Moment (Nm) = F (kN) × armlængde (mm)
The effective area applies in the cylinder's normal working range. With too long stroke length (poor re-adjustment) the force drops because the diaphragm is about to bottom
| Symbol | Meaning | Unit |
|---|---|---|
| tryk_bar | Brake pressure in cylinder (gauge on test connection) | bar |
| cylindertype | Cylinder type (effective diaphragm area in in²) | — |
| armlaengde_mm | Brake arm length (camshaft centre to fork pin) | mm |
| = | Force on tie rod | kN |
| = | Moment on the brake cam | Nm |
| = | Effective diaphragm area | cm² |
Does not apply when
The calculator's own default values inserted. The figures are calculated with exactly the formula the tool uses.
Substituted
Giver
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Når du vælger en ny bremsecylinder, sammenligner to aksler, eller vil forklare chaufføren hvorfor en for lang slaglængde giver dårlig bremse, kan du regne kraften og momentet ud. Cylinderens type er dens effektive membranareal i kvadrattommer.
En styreaksel har type 24-cylindre og 140 mm bremsearme. Ved fuld bremsning måler du 6 bar.
It means: Membranarealet er 154.8 cm², kraften på stødstangen 9.29 kN, og bremsekammen får 1,301 Nm.
Drivakslen har type 30 og 152 mm arme, også ved 6 bar.
It means: Her bliver kraften 11.61 kN og momentet 1,765 Nm. Større cylinder og længere arm giver drivakslen mere bremsemoment, hvor den bærer mest last.
Ved en let opbremsning måler du kun 2 bar i samme type 24-cylinder.
It means: Kraften er 3.1 kN, og momentet 434 Nm. Kraften følger trykket lineært.
1 bar på en type 24-cylinder giver ca. 1,55 kN.
Moment divideret med armlængden skal give kraften. Dobbelt tryk skal give dobbelt kraft.