A multiple-chain trenching machine comprises a prime mover with a trenching head assembly operably connected thereto, the head comprising: a) a frame operably connected to the prime mover at a proximal end; b) one or more pairs of proximal and distal primary sprockets mounted on the frame; c) a primary endless-chain digging assembly engaged around each pair of primary sprockets; d) one or more pairs of proximal and distal secondary sprockets mounted on the frame; e) a secondary endless-chain digging assembly engaged around each pair of secondary sprockets. The primary chains are substantially wider than the secondary chains, and trenching head is adapted so that each of the secondary chains produces a relief slot in the leading edge of the trench. The primary chains are driven in a forward chain direction, while the secondary chains may be driven in a forward or a reverse chain direction.
RELATED APPLICATIONS
This application is a continuation-in-part of prior-filed non-provisional application Ser. No. 09/502,402 filed Feb. 10, 2000, now U.S. Pat. No. 6,397,501 issued Jun. 4, 2002, which in turn claimed benefit of prior-filed provisional App. No. 60/119,699 filed Feb. 11, 1999. This application is also a continuation of prior-filed non-provisional application Ser. No. 10/102,065 filed Mar. 19, 2002 which is in turn a continuation-in-part of said prior-filed non-provisional application Ser. No. 09/502,402 filed Feb. 10, 2000, now U.S. Pat. No. 6,397,501 issued Jun. 04, 2002. Non-provisional application Ser. No. 09/502,402, non-provisional application Ser. No. 10/102,065, and provisional App. No. 60/119,699 are each hereby incorporated by reference as if fully set forth herein.
