Hydraulic breakers for excavators by GORE

What is a hydraulic breaker?

A hydraulic breaker is an excavator attachment that turns oil flow into a fast run of heavy blows. Inside the body a piston strikes a steel tool, which drives each blow into rock, concrete, asphalt or frozen ground.

Many manufacturers call the same attachment a hydraulic hammer. On UK sites you also hear rock breaker or simply the breaker.

The excavator supplies the oil and holds the breaker against the material with down pressure. You fit one where a bucket cannot get through: trench rock, concrete walls and slabs, oversize boulders, frozen ground.

How does a hydraulic breaker work?

A hydraulic breaker works on oil from the excavator, which drives a piston up and down inside the cylinder. High pressure acts under the piston all the time. The control valve switches the chamber above the piston between high and low pressure, and that switching makes the piston cycle.

As the piston rises, it compresses nitrogen in the back head. At the top of the stroke the valve switches, and oil and gas drive the piston down together. The piston strikes the tool, and the tool passes the blow into the material.

The valve does all the timing itself. The operator only positions the breaker and presses the switch in the cab. The four-step drawing of the cycle is in the control valve section above.

How to choose the right hydraulic breaker for your excavator

Matching a hydraulic breaker to an excavator comes down to five checks, taken in order. The machine's weight narrows the choice to one or two models. Oil flow, working pressure and the hitch then confirm the fit, and the job settles the rest.

Hydraulic breaker size and excavator weight

Start with the excavator's operating weight. Each GORE model lists the machine weights it is built for, from 1.2⁠–⁠3 t on the G450 to 10⁠–⁠19 t on the G1000.

A breaker that is too heavy loads the boom, stick and hitch, and the machine loses stability at full reach. One that is too small hits too lightly for the job, so every metre of trench takes longer.

Hydraulic breaker oil flow

Every breaker is built for a set oil flow, given in litres per minute. Across the GORE series it runs from 20 to 110 l/min.

With too little flow, the breaker cannot reach its blow rate. Too much, and the extra oil turns into heat and wear in the breaker and in the excavator's hydraulics. Check the flow your machine's auxiliary circuit delivers, not the total from the pump. The figure is in the excavator's manual or on its spec sheet.

Hydraulic breaker working pressure and relief setting

Working pressure has to sit inside the breaker's stated range too. On GORE models it runs from 88⁠–⁠117 bar on the G450 to 147⁠–⁠167 bar on the G1000.

The relief valve on the breaker circuit is set 5 to 10 kg/cm² below the excavator's main relief setting. That keeps the pump protected while the breaker gets the pressure it is built for. Oil leaves the breaker through the return line and goes back to the tank through the filters.

Hydraulic breaker hitch

The hitch on the breaker has to match the quick hitch on your excavator, size for size. GORE breakers take S-type hitches from S30 to S60, matched per model, from the G450 on S30 to the G1000 on S60.

The hitch is not included in the breaker price. You pick it in the hitch picker on the model card, so you pay for one hitch: the one your machine takes.

Hydraulic breaker for the job: rock, concrete or demolition

Two excavators of the same weight can need different breakers, because the work differs. For hard rock and thick reinforced concrete, take the heavier model your machine can carry. For trenching, light demolition and frozen ground, a model in the middle of your range is usually enough.

The job also picks the tool. Points go into rock; a chisel suits concrete, and a blunt tool takes oversize blocks. The tools section below covers each shape.

Hydraulic breaker installation: hammer lines and oil flow

Does your excavator need hammer lines? Yes. A hydraulic breaker runs on its own circuit, fed from a service port on the main control valve.

The pressure line, marked IN, takes oil from the pump to the breaker. The return line, marked OUT, takes it back to the tank through the filters. In the cab, an ON/OFF switch works the breaker control valve, and two stop valves on the arm close the lines. A relief valve protects the circuit. If the excavator's main control valve has no pressure control valve, one is added.

Before the first job, set the flow inside the model's l/min range. The relief goes 5 to 10 kg/cm² below the excavator's main relief.

Hoses, from the manual: 1/2 inch × 1,450 mm at 140 bar up to the G750. The G850 and G1000 take 3/4 inch × 1,850 mm at 170 bar.

Mounting uses the bucket's pin points. Set the breaker on level ground, take out the bucket pins and line the arm up with the pin hole. Fit the pins, extend the bucket cylinder to the link hole and lock the pins with stop rings and a double nut. Then connect the hoses to the stop valves on the arm, warm the machine up and open the valves.

What size hydraulic breaker do I need?

The right hydraulic breaker size starts with your excavator's weight, and oil flow and pressure confirm it. Find your machine's weight in the first column, then check that its auxiliary circuit delivers the flow and pressure on the same row.

The ranges overlap on purpose, because two machines of the same weight can have different hydraulics. An 8-tonne excavator, for example, sits inside both the G750 range and the G850 range. In an overlap, ask which breaker suits the job, not only which one suits the weight.

Hydraulic breaker for rock

Rock is the main job for a hydraulic breaker, and the tool comes first. Fit a moil point, the standard tool for general breaking where you need no accurate cut, or the conical point.

Start at an edge or an existing crack, where the rock has room to move. Keep the tool square to the face and let the excavator hold steady down pressure. If a spot has not opened within 30 seconds, lift the point and set it a little further in.

Boulders too big for the bucket or the lorry split the same way, from a crack or an edge.

Hydraulic breaker for concrete and demolition

For concrete and demolition, a hydraulic breaker usually runs a chisel. The manual lists the chisel as the usual demolition tool. You can cut in line with the work or across it, depending on how you want the concrete to split.

On concrete pads and oversize blocks, the blunt tool cracks the piece instead of punching a hole through it.

Break slabs from the edge inwards, in pieces the bucket can load, and cut the reinforcement as it shows. Asphalt and the concrete under it come up the same way on road and yard jobs.

Hydraulic breaker tools: points and chisels

A hydraulic breaker takes five tool shapes, and the shape decides how the material breaks. Tool size follows the model, from 45 mm and 8 kg on the G450 to 100 mm and 57 kg on the G1000. The manual's tool section states that the tools are heat-treated for resistance to breakage and wear.

Hydraulic breaker moil point

The moil point is the universal tool, coded M in the manual and the standard type supplied. It suits common breaking in rock and concrete where an accurate cut is not needed. If you keep one tool on site, keep this one.

Hydraulic breaker conical point

The conical point, coded C, has a round, cone-shaped tip. It is the second pointed tool in the range, used for point breaking in the same way as the moil. On a new pointed tool, the manual counts up to 5 mm of length lost at the tip as normal wear.

Hydraulic breaker chisel (H- and V-wedge)

The chisel has a flat blade and comes as an H-wedge or a V-wedge. It is the usual demolition tool, set in line with the work or across it. Its tip counts as normally worn once it is narrower than two thirds of the tool body's diameter.

Hydraulic breaker blunt tool

The blunt tool, coded B, has a flat face. It is made for oversize material and concrete pads, where a chisel point would go through too quickly. The flat face spreads the blow, so the block cracks instead of being drilled.

Hydraulic breaker technique: getting the most from it

A hydraulic breaker breaks best when the blows do the work and the boom only holds it in place. The manual's working rules come down to four habits.

Keep the tool square to the surface

Set the tool at right angles to the surface before the first blow, and keep it there as the material moves. Each blow then runs straight down the tool, and the tool and bush wear evenly. Hold enough down pressure to keep the tool seated, with at least 100 mm of stroke left on the excavator's cylinders.

Move the point after 30 seconds

Give each spot up to 30 seconds. If it has not cracked by then, lift the tool and set it a little further in from the edge. A fresh spot near an edge or crack gives the material room to split.

Stop as soon as it breaks

Let go of the switch the moment the material splits. Blows into empty space, known as blank firing, put the energy back into the breaker. The manual links them to wear on its major components.

Work to the front and rear

Break with the breaker in line with the machine, in front of it or behind it. The boom and arm then take the load in the direction they are built for. Turn the excavator to face the work rather than reaching out to the side.

Hydraulic breaker service and maintenance

Hydraulic breaker service runs by the hour meter, and the GORE manual sets each interval. Most checks are quick ones done on site; the bigger work comes at 1,000 and 2,000 hours. Log the hours from day one, as the first retightening falls due after 10.

Hydraulic breaker construction: three parts and through bolts

A hydraulic breaker body is built in three main parts, and knowing their names makes ordering spares simpler. At the top sits the back head with its nitrogen chamber. Below it, the cylinder holds the piston, which the control valve drives up and down. The seal retainer at the top of the cylinder keeps gas and oil apart. At the bottom, the front head carries the ring bush, the front cover and the pins that retain the tool. Through bolts run the length of the body and clamp the three parts together.

Hydraulic breaker nitrogen pressure

Check a hydraulic breaker's nitrogen charge, 16 to 17 kg/cm² on the G450 to G1000, every 10 hours or once a day. Do it with the breaker at normal temperature, and use nitrogen only. The manual's chart sets the charge against the outside temperature, from −20 to 40 °C.

The charging set connects a nitrogen bottle through a gas hose and gauge to the charging valve on the back head.

Hydraulic breaker oil: temperature and viscosity

A hydraulic breaker runs on the excavator's oil, so the oil's condition sets how it performs. In use, the manual asks for a viscosity of 20 to 40 cSt and an oil temperature held between 40 and 60 °C. If the excavator has no oil thermometer, fit a reliable one.

Run ISO VG 68 in hot weather and ISO VG 46 in cold weather. The manual lists grades such as Shell Tellus 68 and 46 or Mobil DTE 16 and 15.