Patent ID: 8209889

Claim:
An operator guided trencher comprising: a wheeled carriage; an operator handle bar mounted with said carriage; and a trenching chain assembly mounted at said carriage, said assembly including a chain and a multi-sprocket chain guide, said chain guide including a chain bar and a pivotable sprocket mount pivotably maintained at said carriage and having a first idler sprocket rotatably mounted thereon, a biasing spring connected between said pivotable sprocket mount and said carriage, said chain bar having second and third sprockets mounted adjacent to opposite ends thereof in a fixed relationship, one of said second and third sprockets being driven, said first idler sprocket of said chain guide thus pivotable relative to said carriage on said pivotable sprocket mount both against bias of said spring and under the influence of bias of said spring toward and away from, respectively, said chain bar to tension said chain during chain use while also allowing said sprocket to pivot to thereby partially relieve chain tension during chain use in case of debris entrainment adjacent to said chain.