Sokhi Heli-Wom Gears Private Ltd. Manufactures Worm Gearboxes with Close Grain Cast Iron. Sokhi Heli-Wom Gears Private Ltd. Is an ISO 9001:2000 accredited company. The Worm Gearboxes with Close Grain Cast Iron are used for economic mass production, comprehensive maintenance of stocks, favorable delivery period, and ease of servicing.