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
- 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