Ukuqulunqwa okuqhubekayo okungaphambili - kunye nendlela yokwakha eyahlukileyo, ukwenziwa kwe-curble inikwe umzobo wangaphambi kokwenza inyathelo lokwenza oko. Ezinye zeeyunithi zokwenza kwangaphambili zisetyenziswa kwangaphambili zii-hydraulic okanye oomatshini kunye nokuqengqeleka. Inkqubo eqhubekayo inikezela ngenzuzo, ngakumbi i-aluminium, ukuba inkqubo emfutshane ibandakanya ukuphola kancinci kwecandelo kunye namaxesha aphezulu aphezulu anokufikelelwa. Ingxaki yokuba inqanaba lokuseka lihlala linqunyelwe kwinkqubo yokwenziwa kwaphambi kokwenza, kuba kuphela amandla anqongopheleyo kwaye amandla anqongopheleyo afumanekayo kwi-strooke enye (yeendaba) okanye inguquko enye.