Page 2 • Fishing Bumper Subs • Manual D450
2 • Logan Fishing Bumper Sub
OVERVIEW
The Logan Fishing Bumper Sub is a
relatively inexpensive, dependable me-
chanical accessory tool that is suitable
for all shing operations — especially
harsh, downhole applications and deep
workover operations. It can also meet
the demands of tools that require sharp,
sustained bumping action to actuate
or release them.
The primary purpose of the Fishing
Bumper Sub is to enable the operator
to release the shing tool in the event
it becomes impossible to pull the sh.
It can provide the necessary vertical
impact in either direction — upward or
downward — and deliver the required
torque to release the tool from the sh
whether it is rotating or not. The tool’s
design allows full torque and unre-
stricted uid circulation at all times. The
Logan Fishing Bumper Sub can bump
up or down to engage or disengage
overshots or spears, or be used as a
feed-off tool in milling or cutting opera-
tions.
There are several secondary uses for
the Logan Fishing Bumper Sub: to
bump down, to bump a solid downward
blow, and to jar up in the hole. Other
typical operations include releasing
stuck drill pipe, drill collars, tubing, test
tools, and safety joints. The shing
bumper sub can be used in conjunction
with an overshot or spear.
USE
The Logan Fishing Bumper Sub is
especially suited for deep shing
operations and light to medium drilling
applications. Equally effective in either
direction, the tool is also ideal for coring
operations.
The Logan Fishing Bumper Sub deliv-
ers the sharp downward blow and
torque required to disengage a sh
when it is impossible to pull the sh.
The tool can repeatedly bump in either
direction or alternately bump up and
down to dislodge drill pipe, reamers,
drill collars, bits, or other tools that have
become stuck.
The immediate bumping action prevents
cuttings and cavings — especially sticky
caving or heavy mud formations —
from settling and wedging the drill string
making it well suited for light to medium
drilling operations. The tool is equally
effective in either direction. If neces-
sary, the operator can manipulate the
drill string and deliver forceful blows to
release the string. The free stroke fea-
ture enables the operator to accurately
control the weight on bit or other tools.
When properly used, this feature will aid
in maintaining a straighter hole, thereby
resulting in improved penetration and
less bit wear.
The Fishing Bumper Sub is also an
excellent safety device when working
in very deep, crooked holes, and drilling
out cement in heavy mud. The oper-
ator can manipulate the drill string as
needed and deliver forceful blows to
release the string if necessary.
The Logan Fishing Bumper Sub is also
an ideal tool for coring operations. The
bumping action effectively breaks cores
sharply and cleanly for easy removal.
CONSTRUCTION
All components of he Logan Fishing
Bumper Sub are constructed from high-
strength, heat-treated alloy steel to with-
stand severe stress caused by tension,
jarring, and torque.
The Fishing Bumper Sub is composed
of ve major parts: a mandrel, mandrel
body, middle body, knocker, and a top
sub. The critical seal point between
the middle body and knocker is tted
with a knocker seal/ring assembly con-
sisting of an o-ring seal, seal protector
ring, and a seal non-extrusion ring to
increase the life of the rings and prevent
o-ring extrusion.
The Logan Fishing Bumper Sub comes
with a standard box top connection and
a pin bottom connection. Special con-
nections, including left-hand threads,
are available upon request.
Mandrel
The hexagon-shaped mandrel ts into
the matching shape of the mandrel
body. The mandrel freely moves up and
down to provide a continuous source of
downhole torque transmission through
the mandrel body whether bumping or
not. The standard 20-inch stroke length
is suitable for most purposes, although
longer stroke lengths of 30, 36, 42, 48,
and 60 inches are available. The ends
of the mandrel are made up with a
knocker at the upper end and a mandrel
body on the lower end.
Mandrel Body
The mandrel body slides on over the
mandrel. The hexagon-shaped inside
diameter of the mandrel body matches
the shape of the mandrel. Transmitted
torque is conveyed to the running string
through the mandrel, middle body, and
attached tool.
