Erkat rotary drum cutters; robust, reliable tools

By: Drumcutters  06-Dec-2011
Keywords: Excavator, Technical Information, Excavator Attachments

Rotary drum cutters or rock cutters are hydraulic excavator attachments designed to increase the range of work available to excavators and increase their return on investment.

Benefits of rotary drum cutters, sometimes known as rock cutters

  • low vibration levels, almost vibration free
  • low noise levels
  • accurate excavation profiles, due to their low energy impact cutting action, drum cutters can be used to create accurate, smooth surfaces
  • small particle size, material produced is ideally sized for use as back-fill without need for expensive crushing
  • high production rates in soft to medium hard materials


  • tunnelling
  • trenching
  • demolition
  • refurbishment
  • quarrying
  • foundation work
  • under water excavations
  • forestry clearance
  • soil mixing
  • slag removal in steel industry

How to choose the correct size rock cutter for my excavator?

Matching the correct size rock cutter with the excavator is important.

  • the rock cutter must be strong enough to take the weight of the excavator and the excavator must be strong enough to take the energy transmitted back into the machine from the drum cutter
  • the weight of the rock cutter must not destabilise the excavator
  • rock cutters get their power from the hydraulic flow and pressure from the excavator.  Optimum cutting performance is achieved when the hydraulic motor in the drum cutter matches the hydraulic output from the excavator's pumps

To see which rock cutter models are suitable for any particular excavator, please use the "SEARCH" facility above, select the manufacturer from the drop down list shown above and press "GO".  You will find a table listing models of excavators, pump capacity and recommended models of drum cutters.

We try to keep this information upto date but cannot gaurantee that all technical information is correct.  Please contact us if you cannot find your model excavator or if you need any assistance.

MOTOR SIZES e.g. ER 250-2, ER 250-3, etc

By changing the cam ring in the hydraulic motor from an ER 250-2 to an ER 250-3 for example, the volume of oil per revolution of the hydraulic motor is increased.  This increases the power required per revolution which translates into higher torque and higher productivity.  In this way, the hydraulic motor in the drum cutter is matched to obtain the optimum performance from the pumps in the excavator. 

Nothing can be gained by selecting a rock cutter fitted with a hydraulic motor that requires 190 l/min of oil to obtain maximum performance when the excavator can only supply 150 l/min!!!

 The time required to convert a motor from one size to another is approx. 1 hour.

1 or 2 Pump Availability

The majority of excavators are fitted with two pumps.  As an example, the 17 ton CASE CX 160 has 2 x 136.7 l/min pumps.  The primary function of one pump is to drive the main functions of the excavator and the second provides oil for the attachments. 

The ER 600 rock cutter is the ideal size for this excavator but the ER 600-1 motor requires 120 l/min and the ER 600-2 motor requires 150 l/min.

If the oil flow from only one pump is available then the -1 motor size is correct but if the pumps are connected so that they can both provide flow for the attachment, then the -2 motor can be used.

Operating limits in terms of rock hardness for drum cutters

Power is required to fracture material such as concrete or rock.  As the compressive strength of the material increases, more power is required to fracture it.  The power available from the drum cutter is limited by the hydraulic motor and the power available from the excavator.  As drum cutters increase in size, they have larger hydraulic motors, take more power from the excavator and are capable of cutting harder rocks.

Please see the Compressive Strength Table for Common Rock Types in the box below to see the operating limits for each size of drum cutter.  This table is intended as a guide and in some conditions, these limits can vary.

What production rate can I expect from a drum cutter?

The Productivity Table in the downloads below can be used as an indicator of the productivity rates that can be achieved within the operating range of rock hardness suitable for rotary drum cutters.

These levels can vary by as much as plus/minus 15% depending on:

  • size of hydraulic motor
  • cutting direction (wall, floor, trench, etc)
  • operator experience
  • ground conditions e.g. layers, fissures, weathering, etc

1. ER 50 18 kW output

For mini excavators up to a maximum weight of 3 tons. Recommended for light work only and in material up to 20 MPa.

2. ER 100 30 kW output

ER 100 - excavators 3 - 7 ton, 30 kW power Robust, small drum cutter, recommended for use in materials up to 25 MPa. Fitted with 15mm shaft picks.

3. ER 250 45 kW output

ER 250 - excavators 7 - 15 ton 45 kW power Available with standard drums, planing drums or as longitudinal cutter drum

4. ER 600 65 kW output

Suitable for excavators 10 - 20 tons 65 kW power Fitted with one 65 kW hydraulic motor, recommended for material up to 50 MPa

5. ER 650 90 kW output

Suitable for excavators 15 - 25 tons 90 kW output Two hydraulic motors and a more robust housing makes this suitable for material up to 70 MPa. Available with standard, tunnel profiling and planing drums.

6. ER 1200 120 kW output

Suitable for excavators 20 - 40 tons 120 kw output Middle of the range drum cutter suitable for materials up to 80 MPa

7. ER 1500 120 kW output

Suitable for excavators 20 - 40 tons 120 kW output Same hydraulic motor as the ER 1200 but drums fitted with heavy duty pick boxes. Suitable for material up to 80 MPa. Available with a range of cutter drum widths and with tunnel profiling or planing

8. ER 2000 160 kW output

Suitable for excavators 30 - 50 tons 160 kW output Recommended for operation in material up to 100 MPa and available with standard or tunnel profiling drums.

9. ER 3000 200 kW output

Suitable for excavators 45 - 70 tons 200 kW output Recommended for operation in material up to 130 MPa

9a. ER 5500 350 kW output

Suitable for excavators 70 - 125 tons 350 kW output Two hydraulic motors provide enough power for this to work in materials up to 160 MPa

Downloads Relating to Product Range

Keywords: Benefits of Rotary, Drum Cutter, Excavator, Excavator Attachments, Excavator Rock, Forestry Clearance, Hydraulic Excavator, Hydraulic Excavator Attachments, Hydraulic Flow, Hydraulic Motor, Rotary Drum, Search Facility, Slag Removal, Soil Mixing, Technical Information,

Contact Drumcutters

Email - none provided

Print this page

Other products and services from Drumcutters


Grinders for tree stump removal or cutting

For those looking for the maximum flexibility with a drum cutter excavator attachment, the option of fitting special wood cutting picks into the standard pick boxes allows the drum cutters to achieve reasonable performance in wood cutting applications with low capital expenditure. Increased performance can be obtained from drum cutters supplied with special wood cutting drums fitted with non-rotating cutter teeth.


Longitudinal drum cutter - Drumcutters

Suitable ofr excavators 10 - 25 tons 65 kW output Same hydraulic motor as ER 400 L, ER 450L has 450mm and ER 600 L has 535mm diameter drum. Due to its unique design, people have found other applications where the longitudinal drum cutter can be used. Longitudinal drum cutters can be supplied with an adaptor that allows them to be used as an auger drive unit.


Auger drive units - Drumcutters

Owners asked whether their longitudinal drum cutters could be used as rotary heads so Erkat designed an adaptor that could be attached to the output shaft for this purpose. Although extremely useful for some applications, the standard longutidinal drum cutter plus adaptor was too long and too expensive for use as a dedicated auger drive unit.


Accessories for use with rotary drum cutters

Rotators are an essential tool to obtain maximum productivity in specialist applications such as tunnel profiling, renovation of large surfaces, profiling diaphragm walls and working in limited space. The complete range of pick boxes are available from stock including heavy duty pick boxes fitted with hardened steel inserts for great wear resistance and longer working life.


drum cutter with cutter wheel or wheel cutter

Cutting short lengths of narrow, shallow trenches in hard material can be a problem especially when the length of trench does not justify the use of a full scale trenching machine. Drum cutters fitted with a wheel cutter provide an alternative solution and under the right circumstances can be extremely cost effective. ER 100 Max wheel dia 650 mm, max cutting depth 210 mm. ER 1200 Max wheel die 1000 mm.