back holes

back holes

[′bak ‚hōlz]
(mining engineering)
The holes which are shot last in mine shaft sinking.
References in periodicals archive ?
This, in conjunction with smaller than feasible drain back holes in the heads and block, create a "frying pan" effect by breaking down new oil faster and leaving sludge in the engine, which ultimately gets blocked.
RNRC0016 and 29 are forward and back holes to RNRC0017 and RNRC0003 respectively.