The document discusses powered capstans, which are traction winches that provide additional lifting force on cables to augment lifting capacity, stabilize tension, and reduce cable crush. It specifically describes the MK-8 capstan, which can provide working tensions from 0-4500 lbs and 0-9000 lbs to assist with cased hole operations. The capstan is positioned between the well and main winch to handle hoisting work and allow constant tension regardless of cable direction. Key benefits include reducing spooling tension, drum loading, and cable crush while providing additional line pull.

1. Powered Capstan
(also known as a Power Sheave, Capstan Winch or Traction Winch)
The powered capstan is a traction winch that provides additional lifting force on the cable. It
works in sync with the main winch to augment lifting capacity, stabilize cable tension and
reduce cable crush.
The main benefits provided by this device are:
1. Reduces spooling tension to help alleviate cable crush
2. Reduces drum loading to help prevent drum failures
3. Can be operated going into and out of the well to maintain wireline spooling
profile
4. Torque unit replaces top sheave and reduces load on rig up equipment
5. Provides additional line pull to assist hoist unit
MK-8 Powered Capstan
As well’s get deeper and more challenging Zone Power continue to see an increase of cased
hole operations requiring assistance with cable protection. Our new MK- 8 capstan has the
ability to assist the wireline with a working tension from 0 - 4500lbs and 0 - 9000lbs. This is
ideal for chased hole operations. The new multi purpose power pack is capable or operating
9-18K capstans this enables the operator to reduces cost and increases ROI

2. Ideally, wireline cable should be spooled off the drum and back onto the drum at the same
tension. However when the wireline is coming up-hole the line tension is much greater than
when it is going down-hole. The Powered Capstan is positioned between the hole and the main
winch to handle the main hoisting work. This allows constant tension between the capstan and
the main winch drum. A controlled target tension on the main winch is delivered regardless of which
direction the cable is running.
The Power Capstan can give up to 9,000 lbs hoisting assistance thereby allowing standard winch units
to be used beyond their normal operating range and removing the need for custom winches. The
Powered Capstan automatically maintains a screen selected "TARGET" tension on the main winch with
the cable running in either direction. The Powered Capstan thereby eliminates “cable crush” on the
drum.
A typical 4,000 lbs target can be maintained on the winch whether the actual well tension is 13,000 lbs
when hoisting, or only 200 lbs when running cable down-hole into the well.
Capstan in derrick
The system is fully automatic and controls synchronize
the movement of the capstan and the main winch as
determined by winch operator. The system allows
speeds up to 300ft/min and can run multiple tools.
The capstan can be used either secured to the
horizontal deck or supported vertically in the derrick by
the elevators.
The capstan is designed for minimal maintenance
needs.
The steelwork has 10 year corrosion protection.
The entire units is a 3 part lift, all with DNV 2-7.1
certification.
The capstan and power pack can be certified to:
DNV classifications
ATEX Zone II
CE Marking
Class 1 Division 2
Class 1 Zone 2
Features

3.  Suitable for Open Hole and Cased Hole operations without changing the capstan.
 Multi purpose power pack reduces cost and increases ROI
 Operator friendly package design
 Adds to wireline safety as all high tensions are contained in the derrick
 Allows deep deviated high tension wells to be managed
 Advantage over other conveyance methods
 Improves cable life
 Reduces conductor failure
 Eliminates cable crush
 Cable head can be retained for speedy rig up
 Improves productivity
 Reduces operating cost
 Reduces drum stress
Benefits
Product Specifications
The grooves are machined to suit the selected
cable and are interchangeable.
Freewheel speed exceeds the normal winch
operating range. The control system achieves an
extremely smooth application of rim pull to the
running or static cable. The winch is supplied in a
Transit Frame, easily removed from the side or from
the top, complete with lifting slings.
The winch can be mounted horizontally to the deck
or vertically in the derrick.
The winch is hydraulic powered and can be certified
to:
DNV classifications
ATEX Zone II
CE Marking
Class 1 Division 2
Class 1 Zone 2
Capstan Winch 4.5K - 9K Pounds
Wire line cable is carried around twin 31" diameter torque wheels by steel segments
machined to give 180° of support to the cable diameter.

4. Programmable Logic Controller (PLC) allows selection of "TARGET" tension
 PLC automatically maintains the winch at the selected "TARGET" tension
 PLC maintains "TARGET" tension irrespective of cable direction and well tension
 Winch operator can alter "TARGET" tension while running the job (within design
parameters)
 Operator friendly screen displays all required parameters
 Analog and digital presentation for operator
 Screen options provide six control modes and preferred displays
 Alarms, sounder, settings menu, instrumentation and manual stop
 control of power pack
 The control options allow the program to compute using
 well signal only
 combined well and winch signals
 just the winch signal only
 Provided with it's own transit case - normally ships in the hose basket
Power Pack
The power pack provides hydraulic pressure to the Capstan Winch.
The pressure is generated by either an electric or a diesel prime
mover.
 Optional electric or diesel prime movers
 Suitable for 9 or 18K power capstan.
Can be certified to:
 DNV classifications
 ATEX Zone II
 CE Marking
 Class 1 Division 2
 Class 1 Zone 2
 Detachable 50ft or 100ft hydraulic hoses
 Fitted with 200ft multi core control cables
Control Console
Hydraulic Power Pack
Electronic Control Console
This item has to be under the control of the cab safety shut down system if located in a
pressurized cab and is sited in Zone 2 area.
Main control panel is designed to run two independent inline tension devices, thereby
eliminating the need for any electrical interface to the present well tension circuit