Instant installation
ERB is the fastest way to secure the rock roof when tunneling and mining in both soft and hard rock. The bolts are not sensitive to variations in drill hole diameter.
Instant load bearing
When the hole is drilled, the folded rock bolt is inserted and expanded with water from a high-pressure pump. As soon as the bolt is expanded it squeezes tightly against the rock. The load is carried immediately – no waiting for grout or resin to harden.
Instant safety
ERB rock bolts are made of a steel with exceptional formability properties, ensuring a safe and reliable performance in different rock conditions.
Instant Installation
The expandable rock bolt is an ingenious concept. The omega-shaped tube introduced a brand-new way of securing rock roofs from caving in. It’s a tried and tested technology used all over the world.
ERB rock bolts are made exclusively with high-quality steel from the Nordics and manufactured at a plant in Sweden. Jennmar controls the whole production chain, from iron ore to finished bolts. The steel used is clean with consistent properties and excellent elongation, necessary properties to achieve the rock bolt’s reinforcing qualities.
Since ERBs are installed using water only, there are no potential hazards from chemicals to worry about during installation or afterward. The pure steel bolts can remain in the rock without having any environmental impact.
How ERB Work
ERB bolts are delivered and ready to use. The folded tubes have a closed bushing at the top and a connector bushing at the end, where the pressure hose is attached. The high-pressure water inflates the bolt until it squeezes tight to the hole’s wall.
The whole procedure is simple in all kinds of tunneling and mining operations. The method is suitable for mechanized and manual installation, and the equipment needed is easy to move around and power.
ERB rock bolts are also available in a corrosion-resistant coated version.
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The hole is drilled to the necessary length with standard rock drilling equipment.
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The bolt is inserted with or without the optional face plate.
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A pressure pump is attached and expands the pipe with a pressure of up to 30 MPa.
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The pump is removed, and the rock is secured.
A Full Range of Rock Bolts
ERB comes in a variety of dimensions and load-carrying specifications. They are available with 12, 16, and 24 tonne load capacity. There is also an ERB+ version with higher elongation performance for particularly dynamic rock conditions. ERB and ERB+ can be delivered in a fully wide-gap version. In this case, the folded tube has a wider opening, which makes it more suitable for corrosion protection with a plastic coating.
Get your ERB Rock Bolts Here
ERBs are sold directly from Jennmar sales offices and by selected distributors. ERBs are stocked in several parts of the world to ensure fast deliveries. ERB bolts are delivered bundled for easy handling and transporting. Larger volumes can be shipped in containers directly to the site.
Polymer Coating for Corrosion Protection
ERB and ERB+ bolts can be delivered with corrosion protection from a polymer alloy coating. This will save a step in your production and time and money.
ERB & ERB+ Technical Specifications
Part | ERB 120 | ERB 120+ | ERB 160 | ERB 160+ | ERB 240 | ERB 240+ |
|---|---|---|---|---|---|---|
Bolt diameter
in. (mm) | 1.10" (28 mm) | 1.10" (28 mm) | 1.51" (38 mm) | 1.51" (38 mm) | 1.51" (38 mm) | 1.51" (38 mm) |
Profile diameter in. (mm) | 1.08" (27.5 mm) | 1.08" (27.5 mm) | 1.42" (36 mm) | 1.42" (36 mm) | 1.42" (36 mm) | 1.42" (36 mm) |
Material thickness in. (mm) | 0.08" (2 mm) | 0.08" (2 mm) | 0.08" (2 mm) | 0.08" (2 mm) | 0.12" (3 mm) | 0.12" (3 mm) |
Upper bushing diameter in. (mm) | 1.10" (28 mm) | 1.10" (28 mm) | 1.51" (38 mm) | 1.51" (38 mm) | 1.51" (38 mm) | 1.51" (38 mm) |
Inflation bushing diameter in. (mm) | 1.18"/1.46" (30/37 mm) | 1.18"/1.46" (30/37 mm) | 1.61"/1.89" (41/48 mm) | 1.61"/1.89" (41/48 mm) | 1.61"/1.89" (41/48 mm) | 1.61"/1.89" (41/48 mm) |
Hole diameter in. (mm) | 1.26" - 1.54" (32 - 39 mm) | 1.26" - 1.54" (32 - 39 mm) | 1.69" - 2.05" (43 - 52 mm) | 1.69" - 2.05" (43 - 52 mm) | 1.69" - 2.05" (43 - 52 mm) | 1.69" - 2.05" (43 - 52 mm) |
Minimum breaking load kip (kN) | 26.97 kip (120 kN) | 26.97 kip (120 kN) | 35.97 kip (160 kN) | 35.97 kip (160 kN) | 53.95 kip (240 kN) | 53.95 kip (240 kN) |
Minimum elongation % | 15 % | 25 % | 15 % | 25 % | 15 % | 25 % |
Typical elongation % | 20 % | 30 % | 20 % | 30 % | 20 % | 30 % |
Standard length* ft (m) | 4.92' - 13.12' (1.5 - 4.0 m) | 4.92' - 13.12' (1.5 - 4.0 m) | 7.87' - 19.685' (2.4 - 6.0 m) | 7.87' - 19.685' (2.4 - 6.0 m) | 7.87' - 19.685' (2.4 - 6.0 m) | 7.87' - 19.685' (2.4 - 6.0 m) |
*other lengths upon request |
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