Cable bolts KL - 15,5; KL - 15,5K cable bolts are designed to be used to reinforce ground and rock near mining excavations and in particular near workings in weak strata with lower strength or entering mining pressure zones.

Technical description

Cable bolts are made from cable of Ø15,5 mm and 1+6 structure in accordance with PN-71/M-80236 standard. The following types of bolt can be distinguished:

Cable KL-15,5Plain cable
Cable KL-15,5KBird cage cable bolt

The cable lay of KL-15,5K bolt was modified to form birdcage like bulbs of 100mm in length and 26 ÷ 28 mm in diameter. This ensures a better force distribution affecting the cement grout around the cable. When filled with grout the cages act like stiff bulbs in relation to the cement face. The bulbs remain non-cracked despite considerable forces affecting the cable as radial forces occurring in the wires, which could potentially crush the cement in the bulbs, are relatively light when compared to axial forces.
The shape of the cable considerably affects force distribution around the cable caused by cable displacement in the rock. The bulbs cause considerable forces perpendicular to the hole wall compressing the grout and at the same time reduce compressive forces parallel to the hole axis.


As a result cage cables bolts perform better in the rock, i.e. cable movement in the rock, caused by load intensity, is smaller when compared to plain cable. Cable bolts should have the following mechanical properties :
Rm = min 1420 MPa
Rm = min 1620 MPa
Rm = min 1800 MPa
Approval tests have shown that cement grout hardening is 3 times stronger for KL-15,5K cage cable bolts than plain cable bolts, while the bolt length stays the same.
Square washers, round profiled or flat washers are made of 8 or 10 mm metal plate, and come in sizes from 150 to 300 mm. If elements of mining equipment need to be attached, use washer plates with a side hole or an eyelet.
Three-part clamping ring along with the bearing washer make the roof set.
M30 tensioning sleeve and M30 nut are used to apply the initial tension to the bolt.


Technical data


Cable diameter

15,5 mm

Cage diameter

26 ÷ 28 mm

Cage distance

200, 300, 400, 500, itd.

(ecommended distance 500 mm)

Bolt length

1 ÷ 10 m

Capacity required by regulations

min 150 kN

Useful load

260 kN


Installation procedure

Drill the hole of appropriate length and at least Ø > 25 mm for plain cable or Ø > 38 mm for cage cable bolts. Prepare the cable to be installed (attach a vent pipe of Ø 6 or Ø8 mm to the cable). Insert the cable into the hole letting 15 to 20 cm of the cable out of the hole.
Mount and fix the injection head. Prepare cement and water grout in the mixer. Inject the grout until cement wash appears in the vent tube or the air stops flowing out. After 24 hours fix the bearing washer, M30 sleeve and nut (if included) and the clamp. If the bolt comes with M30 tensioning sleeve and M30 nut, the initial tension of at least 30kN should be applied using a torque wrench with the torque of at least 60 Nm.

NOTE: Installation procedure may differ when adhesives or other equipment is used to install the bolt.

KL-15,5 ; KL-15,5K cable bolts have Certificate of Conformity No. 99/3/2014 issued by “INOVA” Technical Innovation Centre Ltd. in Lubin.