Modh ríofa trastomhas
Trastomhas ciorcail aguisín=(líon fiacla móide 2ha)modal
Trastomhas an chiorcail innéacs=líon modúlach na bhfiacla
Trastomhas ciorcal fréimhe fiacail=(líon fiacla-2ha-2hc)modal
I gcás giaranna caighdeánacha: ha=1,hc=0.25; tógann giaranna neamhchaighdeánacha eile
Mar shampla: M4, fiacail 32
Trastomhas ciorcal aguisín=(32 móide 21)4=136mm
Trastomhas ciorcal innéacs=324=128mm
Trastomhas ciorcal fréimhe fiacail=(32-21-20.25) 4=118mm
Baineann an modh ríofa seo le gach giar modúlach (gan giaranna sealaithe a áireamh).
Léiríonn an modulus méid na bhfiacla giar.
Gear modulus = index circle diameter ÷ number of teeth
Roghnú modúl giair
Is é GB1357-78 an caighdeán náisiúnta do mhodúl fearas.
Modal roghnaithe: {{0}}.1mm, 0.12mm, 0.15mm, 0.2mm, {{10}}. 25mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.8mm, 1mm, 1.25mm, 1.5mm, 2mm, 2.5mm, 3mm, 4mm, 5mm , 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 20mm, 25mm, 32mm, 40mm, 50mm;
Modúil roghnacha: 1.75mm, 2.25mm, 2.75mm, 3.5mm, 4.5mm, 5.5mm, 7mm, 9mm, 14mm, 18mm, 22mm, 28mm, 36mm, 45mm;
Modulus is annamh a úsáidtear: 3.25mm, 3.75mm, 6.5mm, 11mm, 30mm;





