Short answer
For a hydraulic breaker to work properly on a machine, four things must be in place: an auxiliary hydraulic line suitable for a breaker (the hammer line), a valve and control that open and close it, a return line that sends the oil back to the tank as directly as possible and through a filter, and flow and relief pressure set within the range in the breaker’s manual. Once these are confirmed, the breaker is mounted on its bracket, the hoses are connected according to inlet and return, the shut-off valves are opened, the oil is brought to working temperature and the first blows are struck with the tool pressed on the material. The values for flow, pressure and return line back pressure are model-specific and come from the breaker’s manual or from HKM.
The machine first: is there a hammer line?
We covered the order of mounting the breaker on its bracket in the fitting and removal guide, and how to read catalogue flow and pressure figures in the flow and pressure guide. This guide covers the work in between: whether the machine is ready to run a breaker and how the first test is done.
Some excavators and backhoe loaders leave the factory with a hammer line or prepared for one; others have none and need it installed later. The first job is to find out which applies to your machine. The machine’s manual or authorised dealer will tell you; two pipes running along the boom to its end, with shut-off valves at the ends, also show that a line is fitted.
If there is a line, check what it was installed for. A line built for two-way attachments such as shears or grapples may not suit the breaker’s one-way flow and return requirements. On many newer machines an attachment mode is selected from the controls or the display, and that choice changes the return path and the flow; check in the manual whether your machine has this setting.
What does the hammer line include?
- Valve: directs oil to the breaker and opens and closes the line. It may be a spare section of the machine’s main control valve or a separate valve added later.
- Control: the pedal or the button on the joystick the operator uses to run the breaker. Which movement starts the breaker is tried at first installation and shown to the operator.
- Pressure and return pipes: the two lines running along the boom to its end. The breaker uses oil in one direction; inlet and return must not be swapped.
- Shut-off valves: at the boom end, where the hoses connect. They close the line when the breaker is removed; both must be opened when it is fitted.
- Return filter: filters the oil coming back from the breaker before it enters the tank, so wear particles from the breaker stay out of the machine’s system.
- Relief valve: limits the line pressure. It is set to the value in the breaker’s manual; the setting left from the previous attachment is not to be trusted.
The return line is the hidden half of the breaker
If the oil returning from the breaker travels back through the main control valve before reaching the tank, back pressure can build up in the line. Back pressure weakens the blow, strains the seals and heats the oil; it is also listed among the causes in the overheating guide. Breaker manuals give an upper limit for the return line, and the machine’s return path is confirmed by measurement to stay below it.
Flow and pressure: no adjustment without measurement
The auxiliary flow given in the machine’s manual may not be the real flow on site; the gap widens if the line was added later, the hoses are long or the pump is ageing. That is why, at first installation, the service technician measures flow and pressure at the end of the line and brings them within the range in the breaker’s manual. The measurement is taken with the oil at working temperature.
Too much flow makes the breaker look fast, but the excess turns into heat; too little and it strikes slowly and weakly. If pressure is outside the range, the adjustment is made on the machine side, not on the breaker. The flow and pressure ranges of HKM breakers are in the specification tables on the Red Line and Grey Line pages, and you can check the match between your machine and a breaker with the breaker selector.
Points to watch on backhoe loaders and mini excavators
On a backhoe loader the breaker is fitted to the rear backhoe arm. Many manufacturers offer a hammer line on these machines as a factory option; if one is to be added later, it is best installed the way the machine manufacturer recommends. The breaker’s weight and flow requirement are chosen to suit the backhoe end of the machine; you can look up suitable models by your machine’s brand and model in the carrier selector.
On a mini excavator the hose route is tight and it is easy to miss a hose being stretched as the boom moves. After installation, run the boom through its full travel and watch the hose; we explained why this matters in the hose routing guide.
Mounting and first test, step by step
- 1
Confirm the line and the settings
Check against the measurement results that flow, relief pressure and the return path match the values in the breaker’s manual. If no measurement has been made, postponing the first test costs less than running on the wrong settings.
- 2
Mount the breaker on its bracket
Complete the mechanical connection before the hydraulic one. Confirm the bracket fits your machine by fitting it; we explained why a bracket is made to suit the machine in the bracket guide.
- 3
Connect the hoses the right way round
Release the line pressure, wipe the couplings and connect the breaker’s inlet port to the pressure line and its return port to the return line. Confirm the port markings on the breaker and in the manual; a breaker connected backwards will not run or will strain its internal parts.
- 4
Open the shut-off valves
Open both valves at the boom end. With the return valve left closed, pressure builds up in the breaker; this is one of the most common first-start mistakes on site.
- 5
Grease and warm up the oil
Grease with the tool pressed against the ground. Start the machine and wait for the hydraulic oil to reach working temperature, checking meanwhile for leaks at the base of the couplings.
- 6
Strike the first blows on material
Run the breaker in short bursts with the tool pressed fully and squarely on the material. Do not run the breaker with the tool in the air; blank firing is the worst possible start for a new installation.
- 7
Watch the rhythm, the heat and the hoses
In the first minutes, check that the blow rhythm is steady, the hoses are calm and the base of each coupling is dry. If the hoses vibrate heavily, see the hose vibration guide; if the breaker does not strike at all, see the breaker not striking guide.
- 8
Record the values
Write the measured flow, pressure, relief valve setting and installation date in the records of both machine and breaker. These starting values are the only way to notice a change months later.
What to watch in the first hours
We covered what to watch in the first hours in the first hours after delivery guide. One extra rule applies to a new installation: if the body quickly gets too hot to touch, work stops and you go back to the hammer line first; on a new installation the two most common causes of heat are high flow and a restriction in the return line.
Running a breaker loads the machine’s hydraulic system differently from digging, and the oil and filter schedule changes accordingly; we explained this in the machine service plan guide. You can ask which breaker suits your machine and what the line values should be by writing to sales@hkm.com.tr with the model codes.
Do and don’t
Do
- Find out which attachment the hammer line was built for; a two-way line may not suit a breaker.
- Have flow and pressure measured at the end of the line with the oil warm.
- Have the relief valve set to the value in the breaker’s manual.
- Confirm that return oil goes to the tank through the filter.
- Strike the first blows with the tool pressed on the material.
Don't
- Do not run on settings left over from the previous attachment.
- Do not take the main pump’s total flow for the hammer line flow.
- Do not connect inlet and return hoses without marking them.
- Do not leave either shut-off valve closed.
- Do not start at full load with cold oil.