How to measure a breaker tool and order the right one: diameter, length and type

Identify the breaker first, then measure the tool

A tool is designed around the breaker’s bushing and retainer set, so its real identity is the breaker itself: given the brand, model and serial number, the diameter, shank length and groove geometry are read from the record. For HKM breakers, every model’s tool diameter is in the specification table on the Red Line and Grey Line pages.

Measuring is needed in three cases: when the breaker’s nameplate is unreadable, when the breaker came from elsewhere and its history is unknown, or when there are tools in the store that nobody can match to a breaker. We covered where to look for the nameplate and serial number in the guide to ordering spare parts.

Which measurements are taken?

We explained what each part of the tool does in the what is a breaker tool guide; this one focuses on how those parts are measured.

• Shank diameter: the diameter of the part of the tool that runs inside the bushing. It is the most critical dimension in tool choice; we explained why the tolerance is so tight in the tool diameter guide.
• Overall length: from the top face the piston strikes to the end of the working tip. It shortens as the tip wears, so it is not enough on its own.
• Distance from the top face to the retainer groove: the most reliable length measurement, because tip wear does not affect it.
• Retainer grooves: how many there are, the length and width of each and where they sit around the tool. A tool whose groove geometry does not match will not fit the breaker even if the diameter is right.
• Working tip type: moil, chisel, blunt or pyramid; on a chisel tool, the direction of the blade relative to the retainer grooves.

Measuring, step by step

1. 1

   Clean the tool

   Grease, mud and rust inflate the measurement. Clean the shank with a wire brush and cloth and clear out the retainer grooves.

2. 2

   Measure the shank diameter at several points

   With a caliper, measure the upper, middle and lower part of the shank, in two directions at right angles at each point. Write down every value; on a worn shank the largest value is the closest to the original diameter, but it is not equal to it.

3. 3

   Measure the lengths

   Measure the overall length and the distance from the top face of the shank to the start of the retainer groove. If the top face is battered or burred, note it; the length reading is off by that much.

4. 4

   Measure the retainer grooves

   Record the number of grooves and the length and width of each with a caliper. If a groove edge has been crushed by the retaining pin, measure from the sound edge, not the crushed part, and note the damage.

5. 5

   Take photos

   Photograph the whole tool with a tape measure beside it, the top face, the grooves from the side and the working tip, each separately. On a chisel tool, a shot showing the blade and a groove together makes the blade direction clear.

6. 6

   Send the measurements with the breaker details

   Put the measurements, the photos and whatever you know about the breaker (brand, model, serial number, the machine it is fitted to) in one message and say that the tool is worn.

What a worn tool tells you, and what it does not

Diameter and length taken from a used tool are not the original dimensions. The shank thins as it works in the bushing, the tip shortens and the groove edges are crushed under the pin. The measurements therefore narrow down the class but are not used on their own as order dimensions; a tool identified by measurement is confirmed against the breaker’s record or a second measurement.

The shank tells you more than its dimensions: a bright band on one side means side load, deep lengthwise scoring means dust getting into the bore. Read those marks as explained in the guide to the marks on a tool shank so the new tool does not end the same way. A new tool fitted in a worn bushing soon picks up the same marks, so when you change the tool, measure the bushing too.

Choose the tool type for the job

The dimensions make the tool fit the breaker; the type makes it fit the job. A moil point enters the material and cracks it from inside, and is the general-purpose choice; a chisel breaks along a line and wins in reinforced concrete and layered rock; a blunt tool does not penetrate but transfers energy into the surface and breaks large blocks of hard, brittle rock; a pyramid tool sits between moil and blunt and lasts longer in abrasive material. We covered which type wins in which material in the tool types guide, and when abrasive rock calls for a special tool in the hard rock tools guide.

You can order different tool types for the same breaker. As long as the diameter and groove geometry stay the same, changing type causes no fitting problem.

What to put in the order

HKM’s tool production range covers more than 20,000 variants, and tools are made to fit more than 130 breaker brands; you can see the list of brands on the tools page. Production time for tools and spare parts is 5 working days; complex parts such as cylinders are excluded. Send your request to sales@hkm.com.tr or use one of the channels on the contact page.

• The breaker’s brand, model and serial number; the old tool’s code if you know it.
• Dimensions: shank diameter, overall length, distance from top face to groove, number and size of grooves; with a note that the tool is worn.
• Tool type and, for a chisel, the blade direction.
• Photos: the whole tool, the top face, the grooves and the working tip.
• The job: what material it works in and which machine carries the breaker.
• Quantity and delivery address.

Do and don’t