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Correct service and maintenance will prevent premature wearing down and help maintain the safety, dependability and productivity designed into this machine.

Therefore, servicing and machine attending personnel must always be given due time: performing inspections at the prescribed intervals, servicing, cleaning, adjusting and correcting the machine and its equipment must have priority over all other jobs.

This will also aid in anticipating a damage in a beginning stage which, in turn, may save the owner excessive and expensive repairs.

Because of the difficult conditions, dirt, wear and tear under which this machine works, regular service and maintenance are essential, so that the prescribed intervals should be conformed to without fail. Neglect thereof could not only jeopardize the work safety of the machine but would also result in immediate loss of granted equipment warranty


A Special Service for overhauling the cutter gear transmission is required every 1500 hours of operation. However, in extreme work conditions (rock and boulders) the service interval may have to be shortened.

Users are therefore adviced to pay attention to all servicing plans and instructions belonging to the Cutter system - also those of other manufacturers' than WONKANG.

All maintenance carried out must be entered into the supplied Maintenance and Repair log. This is to be done by the person who carried out the job, and to be signed by the same person and a witness (foreman).
In case of a claim for damages, WONKANG will have the right to consult the maintenance log.

For Users Overseas-Spare Parts

When the equipment is used outside Korea and especially in overseas countries, WONKANG recommends that the user be appropriately provided with spare parts right from the beginning of a job. In this way, it may be avoided that the equipment must stand still until missing parts have been delivered.

For this purpose, please consult WONKANG. Skilled staff at WONKANG will readily help you in making a list of such parts that would be recommendable to have in stock for your application and job conditions.


Safety Guidelines


Lubricating and servicing may be performed only when the carrier machine and
all additional power packs are off.

The main switch on the cutting instrument panel in the cab must be at "O" position and accidental starting be prevented.

  • All personnel working with the equipment, or servicing or repairing it, must first read and understand these instructions. Unauthorized or untrained persons may by no means operate the equipment, work with it, handle its tools or carry out maintenance or repair on it,

  • All official safety standards regarding work safety, personal safety and protection as well as prevention of accidents must be strictly adhered to wherever applicable.

  • Personnel carrying out inspection, service or maintenance must wear safety helmet ("hard hat"), and their clothing must fit tightly enough not to catch on rotating or protruding parts. They must also wear the appropriate personal protection for the job such as protective clothing, safety glasses, safety shoes, etc.

  • Personnel carrying out maintenance must have been trained for the job, and be authorized by the contractor to perform it.

  • Personnel working with air jet (cleaning) must wear protective clothing, respirator and eye protection.

  • The equipment must not be started during maintenance: Place "Equipment in Maintenance" tag on control elements to refrain from starting.

  • Be careful when handling with hot lubricants or hot parts.

  • Never perform maintenance or repair in closeness of an open trench: Trench cutter must be traveled away from the trench, to a safe distance therefrom and onto firm and level ground, before repair or maintenance may be started.

  • Never attempt to weld on the hydraulic tank or on any lines containing oil since there is a great risk of fire.

  • Before servicing the hydraulic tank, make sure it is totally out of pressure.

  • Do not perform any setting or adjusting on machine in travel or equipment in operation.

  • At tools and devices used for maintenance must be safe and in good working order.

  • Structural changes on the equipment which could affect its capacities (e. g. its stability) such as extensions, additions, readjustment of overpressure, relief or safety valves etc. may be made only after consultation with WONKANG and upon receipt of a written confirmation from WONKANG. The change may then be made only under supervision of a skilled person appointed by WONKANG.

  • Electrics must be protected against moisture, and cables against damage (e. g. against being driven over).

  • Safety guards on the equipment are for your personal safety. They may be removed only for service, maintenance or repair and then only after the equipment has been shut off and been appropriately protected against accidental starting or abuse. Engine service doors, shrouds, protective gratings, or any other covering of a moving part are safety guards. They must all be promptly and correctly reinstalled after service.

  • Personnel may stand only on the provided gratings and platforms white servicing the equipment. Ascending and descending may be done only by means of the provided treads. Accessways, platforms, treads and hand rails must be maintained walk and work safe.

  • Compressed gas cylinders must not be exposed to extremes of temperature (protect from sunshine). Oxygen cylinders and fittings must be kept free of oil or grease and may not be handled with oily hands or gloves (risk of explosion).

  • The carrier of the equipment must not be towed, or power units and drive gears thereof could get damaged.

General Instructions

Should there be any doubt as to repairing or restarting the equipment, please do not hesitate to consult WONKANG staff. Never attempt to correct defects or perform repairs if there is not the required personal skill or the required special tools are not at hand.

In this way potential damage will be avoided. It is not a shame not to be familiar with all kinds of equipment.

The following instructions must be followed without fail:

  • Before greasing, thoroughly free all greasing points of old grease and dirt.

  • Replace only with parts of the original make.

  • Keep the work place and toots clean.

  • Use clean and fully enclosed containers when handling oils and lubricants.

  • Clean filler necks and lube nipples before refilling.

  • Close filler openings promptly after filling to prevent that dust or dirt enters.

  • Place dust caps on plugs, sockets, couplings and receptacles immediately after unplugging or uncoupling a line.

  • When changing oil, have sufficient oil collecting containers ready and make sure the waste oil is correctly disposed of.

  • Use only the recommended oils and greases.

  • Before changing to an oil product of other brand, make sure it is compatible.

  • Use only fresh oils and greases

Initial Run-ln Services


Observe also the other manufacturers' instructions and specifications
(those for the base machine and winch).

  • Before putting a new cutter-wheel gear case to work, run it without load for 5 hours.

  • Regularly check that the hydraulic system, hoses and couplings are tight (should be done hourly as necessary).

  • Check cutter rope for damage, grease rope swivel and check for easy rotation.

  • Regularly check all limit switches for proper functioning.

  • Daily check that all threaded connections are tight and firm; retension as necessary.

  • After 100 hours of initial operation (and then regularly every 1000 hours), carry out oil change at the cutter wheel gear cases (2 places), the mud pump.


This section contains the servicing plans for the machine. The plans are organized into 10, 50, 250 and 1000 hours of operation.

The prescribed service job is listed in table. Following the table, there are additional services to be carried out regularly in between the above intervals.


It is to the contractor's interest to see to that maintenance is performed
correctly and at the prescribed intervals.

The intervals are organized such that they will coincide as long as normal operation is maintained: when for example the 100 hrs service is due,
the 10 and 50 hrs services will also have to be carried out.

If the equipment is used in extremely dusty or wet conditions it may be
necessary to shorten the lubrication intervals.


- Only Only during running-in period
- △ : First 100h operation with new gear box and new mud pump only.



Before carrying out any maintenance work to the cutter wheels, press the Emergency Stop for the cutter wheels.

Checking the Gear Oil and Refilling

The quantity of oil in the two cutter-wheel gear transmissions must be checked daily or at least after 10 hours of operation when warm from operating, and be refilled as necessary.

The gear oil must also undergo a daily visual inspection in order that any impurities may be detected early on.

To inspect and refill proceed as follows:

  • Unscrew mounting bolts (4) and remove protecting cover (1) from service- and filler hole.

  • Remove screw plug (3).


Fig. Service and filler hole

  • Using a syringe (10 ml), take oil sample and carry out visual inspection for cloudiness and foreign particles in the oil.
    Once a week, pour additional oil sample into test tube and let it stand for about 10 hours. Then check whether foreign particles have settled on the bottom.


If impurities are found in the oil (bentonite, sand…) cutter operation must immediately be stopped to avoid additional damage to the gear transmissions.

Only after opening and complete cleaning, inspection and repair, may the gear transmissions be put into operation again.

While checking for impurities in the oil, the axial face seal must be checked too, and be replaced as necessary.

  • Screw an adapter into the filler hole, and fit an oil filler unit with pump to the adapter.

  • Loosen ball cocks (1 and 2) from cutter frame.

  • Open corresponding ball cock on cutter frame:

    Lefthand cock is for left gear transmission (1). Righthand cock is for right gear transmission (2).


Fig. Oil line ball cocks.

  • Now pump in until oil escapes at ball cock.

  • Close ball cock.

  • Make two more draughts with pump.

  • Remove oil filler unit and adapter.

  • Reinstall screw plug.

  • Reinstall protecting cover and tighten with mounting bolts.

  • Repeat the procedure for the other gear transmission.

Changing Gear Oil

The first oil change of the two cutter-wheel gear cases is to be performed after 100 hours of operation. All subsequent oil changes are due every 1000 hours of operation or once a year (whichever comes first).

For oils to be used, see sect. Approved Lubricans


Waste oil must be collected in a container and be correctly disposed of.

To change gear oil, proceed as follows:

  • Remove side cover mounting bolts (see fig.,arrow) from one cutter-wheel, and withdraw cover.


Fig. Cover mounting bolts

  • Remove ball cocks (1, 2) from cutter frame.

  • Open corresponding ball cock.

       Item 1 is for left gear case
       Item 2 is for right gear case

Fig. Ball cocks


  • The drain / filler screw must be in the lowermost position.

  • On cutter gear cases fitted with extensions obstructing the drain / filler holes (1),

       the oil must be drained and filled through the drain / filler  hole.

  • Remove one of the two provided drain / filler screws.

  • Drain old oil into container.

  • Screw an adapter into the drain / filler hole.

  • Fit an oil unit to the adapter and pump in until oil escapes at ball cock.


If the oil is being changed or refilled after inspection / re-pair work,

the gears must be flushed with fresh oil before refilling.

  • Close ball cock.

  • Make two more draughts with the pump.

  • Remove oil filler unit and adapter, and reinstall drain / filler screw.

  • Reinstall side cover and tighten mounting bolts.                                  

  • Repeat the procedure for the other gear case.


Fig. Drain / filler screws

Checking the Axial Face Seals

The axial face seals on the drive shaft of each cutter-wheel is to be checked at least once a week.
To check proceed, as follows:

  • Hold a container ready and open the seal drain plugs on the cutter frame (1)


Fig. Inspection screw


Fig. Oil drain plugs

  • Collect escaping oil and measure the quantity.


The quantity of oil escaping must not exceed 0.5 l a week. If it does, the axial face seal must be replaced.


  • However, before replacing, check first the mechanical seal of the oil motor to make sure the Oil did not come from the motor.

  • Repeat the procedure for the other cutter-wheel.

Replacing Cutting Teeth

  • Insert new cutting tooth.

  • Tap in expansion pin (1).

  • Knock out expansion pin (1)
    with appropriate tool.

  • Remove old cutting tooth using appropriate tool. (2)


Fig. Removing a cutting tooth

Changing Cutting Wheels

  • ​Clean cutting wheel and gear shield thoroughly.

  • Remove mounting bolts from wheel side cover and withdraw cover.


Fig. Side cover mounting bolts

  • Remove mounting bolts from cutting wheel.

  • With the aid of a mounting bar, press cutting wheel a few centimeters away from gear casing.

  • Secure cutting wheel with a lifting device and pull away from the gear casing.

  • Before fitting new cutting wheel, clean gear casing thoroughly and grease it.

  • Install new cutting wheel and screw tight.

  • Reinstall side cover onto wheel and tighten bolts.


Fig. Cutting wheel mounting bolts


Replacing a Gear Shield


A new cutter gear transmission must be
run-in for 5 hours without load before putto work.

  • Remove cutting wheels from gear shield.

  • Loosen mounting screws of oil motor.

  • Disconnect electric cable to speed transducer.

  • Fit transportation frame to gear shield.

  • Remove mounting bolts from gear shield.

  • Lift off cutter.

  • Install new gear shield with same procedure as above but in reverse order. After installation, the distance from cutting teeth to suction box should not be more than 5 mm and also the distance between the two cutting wheels should not be more than 10 mm.

Replacing and Setting a Speed Transducer (Optional item)

The two cutter-wheel speed transducers are factory-set and require no

However, if a transducer has to be replaced, proceed as follows:


Open the nut only just as much as to enable the transducer to be unscrewed.

  • Open up speed transducer housing. (1)


  • At nut (2), loosen transducer retaining screw.

  • Measure distance 1.

  • At new speed transducer, adjust retaining screw to measured distance.

  • Screw-in new speed transducer into housing and secure with nut.

  • Close housing.

Fig. Cutter-wheel speed transducer

Further Cutter-Wheel Maintenance

In accordance with the servicing plan, the following work still needs to be carried out

  • All bolted and threaded connections must be tightened up every week.

  • Worn-down tooth holders and gear shiels are to be rebuilt by welding.

  • Recommended electrodes ;
    Citodur 600
    Dur 600

Special Service of Cutter Gear Transmission

The gear transmission of each cutter-wheel is a heavy-duty performing component of the cutter.

To guarantee that their maximum capacity be available at all times, they require a special treatment.

Like any other components, the cutter-wheel transmission is subject to natural wear.

The amount of wear depends on the conditions under which the cutter-wheels are used (the type of soil, type of equipped teeth, etc.).

Many years of experience made by WONKANG have shown that a thorough service of the gear transmission is necessary every 1500 hours of operation. In tough operations, like in rock and boulder formations, the special service should be carried out more often, to avoid damage to the gear transmission.

The service comprises extensive maintenance work on the transmission, requiring an expert opinion on the various individual parts.

In avoidance of a costly damage to the transmission, several of the parts which are
essentiai for the functioning of the transmission will be replaced with new parts during the service.

Without such a preventive measure, a failure in the function of for example the shaft seals of the cutter-wheels may be recognized only after bentonite has entered into the gears.

Restoration of a transmission into which bentonite has entered is a troublesome procedure involving replacement and repair on many of the parts.


The service on the transmission shall be carried out only by WONKANG or by an authorized equipment dealer. Neglect in this respect can result in loss of the equipment warranty.

If bentonite in the transmission is not recognized in time, bearings and gears may get so damaged that the whole gearbox may have to be replaced with a new.

In what follows is a table which lists the main components that have to be checked and/ or replaced in the special 1500 hrs. service.

Table for Special service




Replacing the Suction Box


The suction box is replaceable, and must be exchanged when the cutter is
to be adapted to another cutting width.


To change suction boxes, proceed as follows:

  • Remove all cutting wheels.

  • With a lifting device, secure the suction box.

  • Loosen mounting bolts, remove suction box and place it on ground.

Fig. Removing the suction box

  • Remove old O-ring and insert new O-ring. (1)

  • With lifting device, install new suction box
    and screw in place.

  • Screw support for reamer plates (2) onto
    cutter frame.

  • Set adjusting screws (3) such that reamer plates have no play.

  • Reinstall all cutting wheels

Fig. Supports and adjusting screws of reamer plates

Servicing the Suction Box

Recommended electrodes ;

Citodur 600

Dur 600

Gridur G44

The servicing plan for the suction box is as follows:

  • All threaded or bolted connections are to be retightened every month.

  • Worn-down edges and inlet openings must be rebuilt by welding.
    Permissible diameter of openings is 90 mm. 


Fig. Inlet openings


Checking the Oil Level

The oil level in the mud pump system must be checked daily.

The pump is connected to a pressure compensator system which ensures that there is always a slight overpressure in the oil of the pump bearing housing so that bentonite, water or other contamination does not enter into the bearing.

In order that the required overpressure is maintained at all times of operation, the oil level in the system must not be allowed to drop below a specific value.

The actual oil level in the pressure compensator is shown on the compensator itself.
The oil level is indicated by a pin.

Four marks on the half pipe show whether the compensator is filled to proper level.


Fig. Marks on the half pipe

  • Pos. 1 : Compensator is completely empty

  • Pos. 2 : Min. oil level during operation

  • Pos. 3 : Max. oil level during operation    

  • Pos. 4 : Compensator is completely filled


During operation the indicating pin must stand between pos 2 and pos. 3

Fig. Examples for indicating pin positions

Refilling and Bleeding the Mud Pump Pressure Compensation System

  • Connect gear oil refiller to filling inlet "RV" on mud pump. (4)

  • Open ball cock (1).

  • Using the refiller, fill up pressure compensator 1 until oil escaping at ball cock 1 is free of air-bubbles.

  • Close ball cock (1 ).

  • Continue pumping with gear oil refiller until the piston in pressure compensator is extended to the 3rd mark on the half pipe.

  • Remove gear oil refiller from mud pump and reinstall filler screw.


Fig. Refilling pressure compensation system

Checking Oil Quality

  • Open oil drain prug slowly. (1)

  • Discharge some oil into a test tube and then
    reinstall drain plug.

  • Make a visual inspection of the oil sample.

  • Allow the oil sample to stand for approx.
    10 hours and then check for settling or
    separation of impurities.

  • If impurities are detected, the two axial face
    seals on the pump shaft must be inspected,
    and if necessary be replaced. (See checking
    the Axial Face Seals)


Fig. Oil drain plug.

Changing Oil

  • Open ball cock.(see fig. item 1)

  • Remove oil drain plug (2) and let all oil out.

  • Remove second drain plug (located opposite
    to 2) and flush axial face seal with fresh oil.

  • Refill with oil. as described in section Refilling
    and Bleeding the Mud pump pressure
    compensation system.



Fig, Changing oil.

Checking Axial Face Seals

To check the shaft upper end sealing:

The functioning of the upper slide ring seal ( see Fig. item1 ) can be checked at the provided inspection screw (2).

  • Remove inspection screw.

  • Collect escaping oil in a container; with daily inspections, the amount of oil escaping may not exceed 0.05 l.


If this value is exceeded, the axial face seal must be replaced.


Fig. Pump shaft upper end sealing

To check the shaft lower end sealing:


The functioning of the lower axial face seal ( see Fig. item1 )
can be checked at the provided oil drain plug (2)

  • Remove oil drain plug.

  • Discharge some oil into a test tube and then
    reinstall the drain plug.

  • Make a visual inspection of the oil sample.

  • Let the oil sample stand for approx. 10 hours
    and then check for setting or separations of

Fig. Pump shaft lower end sealing


If impurities are detected, the slide ring seal must be replaced.

Removing Mud Pump

  • Remove all mounting screws of oil motor 
    ( see Fig. item1 ) and lift off Oil motor.        

  • Disengage mud hose from pump by loosening
    connecting flange (2).

  • Disconnect cable for speed transducer.

  • Disconnect hydraulic line for pressure compensator.

  • Fasten pump to lifting device.

  • Remove mounting screws from pump retainer ring (3).

  • Remove screws (4) from pump support and lift pump
    sideways out of cutter.

To reinstall the mud pump, use the same procedure but
in reverse order.

Fig. Removing the mud pump

Replacing and Setting the Speed Transducer (Optional item)


The transducer for the rotational speed of the pump
is factory-set and requires no maintenance.

However, if the transducer has to be replaced,
proceed as follows:

  • Open up housing (1) of speed transducer.

  • At nut (2), loosen transducer retaining screw.

  • Unscrew transducer and remove it.

  • Measure distance 1.

  • Adjust retaining screw of new speed transducer to
    above measured distance.

  • Screw in new transducer into housing and secure
    with nut.

  • Close housing.


Open the nut only as much as to enable the
transducer to be unscrewed.

Fig. Speed transducer of mud pump

Adjusting the Impeller

If there is a noticeable decrease in the pump delivery this may be caused by the clearance between the suction-side wear plate (3) and the impeller (2) being too large.

To check the clearance:

  • Remove mud pump from cutter.

  • Use a valve adjusting gauge to measure the width of the clearance through the opening at the suction side.


The clearance Should be set to approx. 0.5 - 1.0 mm.

If the clearance is larger, the impeller is to be readjusted accordingly.

Proceed as follows:

  • Open lock washer (4) between the two slotted nuts (1).

  • Loosen both slotted nuts approx. 2 mm.

  • The impeller can now be rotated by hand an adjusted
    to the correct clearance.

  • Tighten slotted nuts (1) after adjusting the impeller.

  • Measure the clearance again an readjust it once
    more as necessary.

  • Insert lock washer (4) between the slotted nuts to
    secure them.

  • Reinstall mud pump.


In the case of an impeller being stuck, try to loosen it by knocking. slightly onto its front side.

If this is of no use, the pump case is to be dismounted too.

0.5 - 1.0 mm

Fig. Adjusting the impeller

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