Mining Safety in Peru: Replace Timber with Stacko™ and Timba™

To replace timber cribbing in mining workshops, National Plastics & Rubber (NPR, Australia) makes two polyurethane support blocks rated at 30 kg/cm² and tested to AS1170.0: Stacko™, interlocking cribbing blocks that build towers up to 60 tonnes and 150 cm with a 3:1 safety factor, and Timba™, single blocks rated from 18 to 108 tonnes. Endeavant supplies both in Peru.

Why is timber cribbing unsafe in a mining workshop?

Timber was the default workshop support for decades, but it has limits no procedure can fix:

• Unknown capacity: there is no test behind its load. Its strength varies with species, moisture and grain direction, so nobody can calculate it before a component goes on top.
• It splinters, cracks and deforms: repeated loading changes its shape, and splinters injure the hands that handle it.
• It soaks up water and oil: it rots, gains weight and breaks down with workshop fluids.
• It is a consumable: it gets thrown out after a few uses and has to be replaced again and again.

What is Timba™ and how much load does it hold?

Timba™ is a support block made from rigid, high-density industrial polyurethane, designed by NPR as a direct timber replacement in mining workshops, shipyards and manufacturing plants. Each Timba™ block takes a uniformly distributed static load of 30 kg per cm² of bearing area, with a 100 cm² minimum, and its rating was set to AS1170.0 with independent laboratory tests. Its compressive behaviour was verified to ASTM D1621-10, the standard test for rigid cellular plastics.

Timba™ has 0% water and oil absorption, does not splinter or rot, is up to 30% lighter than timber and keeps its capacity with the block between −50 °C and +40 °C. NPR has designed and manufactured its products in Brisbane since 1997.

What Timba™ sizes are available?

There are three series by cross-section, in several lengths. The larger the bearing area, the higher the capacity:

• 100 series (100 × 100 mm section): 600 mm, 3 kg, 18 t (NPR02247-10); 1200 mm, 5 kg, 36 t (NPR02249-10); 1800 mm, 8 kg, 54 t (NPR02248-10).
• 200 series (200 × 100 mm section): 600 mm, 5 kg, 36 t (NPR02140-10); 900 mm, 7.5 kg, 54 t (NPR02637-10); 1200 mm, 10 kg, 72 t (NPR02246-10); 1800 mm, 15 kg, 108 t (NPR02142-10).
• 300 series (solid 300 × 300 mm block): 400 mm, 13 kg, 36 t (NPR02336-10).

Timba™ blocks stack in a vertical pattern (2 blocks for the 100 series, 3 for the 200 series, 4 for its 600 mm length) or a crossed pattern (up to 6 blocks for the 100 and 200 series). The 300 series stacks vertically only, up to 2 blocks.

What is Stacko™ and how much does a tower hold?

Stacko™ is an interlocking cribbing block system made from UV-stabilised virgin polyurethane: each layer locks into the one below, so towers are built to suit each load. The standard triple tower, with 3 blocks per layer, holds up to 60 tonnes and reaches 150 cm. The rating is 30 kg/cm² with the 3:1 safety factor already included, tested to AS1170.0 (2002) as a single block and as a 150 cm tower, across −50 °C to +40 °C block temperature.

Each Stacko™ block (NPR05007-10) measures 510 × 150 × 150 mm and weighs 8 kg, up to 30% lighter than timber and splinter-free. It resists oil, workshop chemicals, salt water, rodents and insects, and can be stored outdoors. As a real example, Stacko™ towers held 29,597 kg under a CAT 785C haul truck.

Which Stacko™ tower configurations are there?

Tower width is set by the number of blocks per layer: the single tower (1 block) holds 23 t up to 45 cm, the double (2 blocks) 46 t up to 60 cm and the standard triple (3 blocks) 60 t up to 150 cm. Combining plates, a jack plate and V-blocks gives eight standard configurations:

• Single block: 30 kg/cm², up to 23 t.
• Tower + top plate, or + plate and top support: 100 kg/cm², up to 60 t.
• Tower + top plate + jack plate: Ø250 mm bearing, up to 60 t.
• Tower + top support: 30 kg/cm², up to 60 t.
• With a V-block, for round loads from Ø15 to 120 cm: tower + plate + V-block up to 40 t, tower + V-block up to 20 t, and a single V-block up to 13 t.

NPR's golden rule: in the standard tower always use 3 blocks per layer on the mandatory base, never 2 blocks or a «bridging» layout. For 2 blocks per layer use the double tower with its own base.

Stacko™ vs recycled plastic vs timber: what is the difference?

NPR's comparison guide puts the three materials side by side. Stacko™ is the only one with a known safety factor, temperature range and deflection:

• Safety factor: Stacko™ 3:1 | recycled plastic unknown | timber unknown.
• Tested temperature range: Stacko™ −50 to +40 °C | recycled plastic +25 °C | timber unknown.
• Deflection at full load: Stacko™ under 2% | recycled plastic up to 20% | timber unknown.
• Block weight: Stacko™ 8 kg | recycled plastic 12 kg | timber variable.
• Storage: Stacko™ outdoor or indoor (UV-stabilised) | recycled plastic indoor only | timber indoor only.
• Tested as: Stacko™ block and 150 cm tower | recycled plastic single block only | timber not tested.

Recycled plastic can claim a higher figure (58 kg/cm²) because it is published without a safety factor or a tower test. Stacko™ publishes 30 kg/cm² with the 3:1 factor already applied: the number you can actually design a support with.

Do Stacko™ and Timba™ work in Peruvian mining conditions?

Yes. Peruvian mine sites combine high altitude, frost in the Andes, heat on the coast and constant exposure to dust, water, oils and fuels, exactly the conditions that break timber down. Stacko™ and Timba™ keep their rated load while block temperature stays between −50 °C and +40 °C, do not absorb fluids, and Stacko™ can be stored outdoors because it is UV-stabilised.

Their documented rating also gives the traceability each site's safety standards ask for: the supervisor can calculate the support's capacity (area × 30 kg) and record it before anyone works under the component.

How do you build a Stacko™ tower safely?

1. Inspect every part for damage and complete your own risk assessment.
2. Place the base on a solid, level surface, with 3 blocks in its slots.
3. Lay the second layer of 3 blocks at right angles to the first and keep alternating to the required height, 150 cm maximum.
4. Top it for the load: top support, top plate, jack plate or V-block. If needed, turn the top layer 90° for a flat surface.
5. To avoid working under suspended loads, build the tower away from the machine and roll it in with the NPR07829-00 safe positioning trolley, whose wheels retract under the load.

Stacko™ or Timba™: which one should you choose?

Choose Timba™ when you need a single block that directly replaces a timber block, for linear or low-height supports, and Stacko™ when you need a variable-height tower for heavy loads, round loads or tight spaces. For a raised haul truck tray there is a dedicated block, Tray Support for dump bodies. The criteria for choosing between all these options are in our guide on how to choose support blocks for mining equipment, and the full range is in the NPR catalogue.

Stacko™ and Timba™ FAQ