Manual D450 • Fishing Bumper Subs • Page 3
Logan Fishing Bumper Sub
•
3
Middle Body
The inside diameter of the middle body
is closely fitted to the outside diameter
of the knocker and top sub at the upper
end. The inside diameter of the middle
body is closely fitted to the mandrel
body at the lower end. The interior
surface is highly polished to reduce
frictional wear.
Knocker
The knocker screws onto the top of
the mandrel. A lock screw on the lower
end of the knocker tightens the knocker
against the mandrel to prevent rela-
tive movement. The knocker material
is specially selected for use in impact
loading. It is closely fitted to restrict high
frequency lateral vibration (chatter) that
can shorten the life of the tool.
Knocker Seal/Ring Assembly
Two seal/ring assemblies are located
on the upper end of the knocker. Each
seal/ring assembly consists of an o-ring
seal, a seal protector ring, and a seal
non-extrusion ring. The non-extrusion
rings prevent the o-rings from being
pushed out or rolled out of position. As
hydraulic pressure is applied (in either
direction), these seal/ring assemblies
reduce normal diametric clearance at
the seal points to nearly zero.
Knocker seal rings, seal protector rings,
and non-extrusion rings are provided on
the standard knocker. Optional chevron
packing sets are available and are rec-
ommended when circulation through the
fishing bumper sub will be extensive.
Top Sub
The top sub is fitted to the upper end of
the middle body and has a box connec-
tion.
Top Sub
Knocker
Knocker Seal Ring
Non-Extrusion Ring
Seal Protector Ring
Middle
Body
Mandrel
Mandrel
Body
Knocker
Lock Screw
