12. Loading and unloading of trucks
- Depending on the series to which they belong, or the type of material from which they are made, Silestone, Dekton or natural stone slabs will be more or less fragile. In such cases, three pieces will be mounted for the racks and/or the vertical support parts of the rack will be lined with wood or polystyrene. Non-slip strips will be inserted between the truck surface and the rack.
- VERY IMPORTANT: When distributing the load on each rack, it must be considered that the front shafts must always bear less weight than the ones at the back. Thus, for example, if the load weighs 24,000 kg, 10,000 kg will be placed on the front rack and 14,000 kg on the rear one (approximate weights).
- If the slabs are not correctly secured with the tensioners or the racks are not assembled properly, the load could shift during the journey and cause the truck to overturn.
- If other products must be loaded between the rack (marketing, flooring material, etc.), this will be done after loading the slabs, through the side doors of the trailer.
Based on these assumptions, the guideline is as follows:
- The loads will be organised and the pallets prepared well in advance, to avoid bridge crane traffic in the work area during the loading process and speed up the operations.
- The driver will reverse the truck into the loading area with the doors closed so that it is properly centred, leaving pedestrian passageways to the right and left and permitting the correct operation of the work equipment (forklifts or bridge cranes).
- The truck must remain completely horizontal in the loading area and the doors to be opened will be secured and chocks will be placed on the back wheels of the trailer before starting to load it, to guarantee it remains completely motionless.
- The trailer will be prepared for loading. In this respect, there are four types of trailers: with low beds (open top), with high beds (closed, rigid or with canvas sheets), platforms and containers. Each one has a different loading procedure.
12.a. Low beds (open)
These trailers have a length of about 5.2m (two axles) or 12.6m (three or four axles). The deck may be made from aluminium. In this case, use racks with a wooden base (to prevent the load from sliding during transport) and load them with the bridge crane.
Their construction may be specially requested.
Once the truck is in place and immobilised, the rear doors will be opened and the stepladder/platform will be put in place so that the trailer can easily be accessed.
Positioning the racks:
In the case of small beds (containing just one rack), it must be centred as much as possible inside the trailer and as close as possible to the rear axle. The ends will be about 1.5m from each other and when possible, three pieces will be inserted to prevent the slabs (natural stone, Dekton or Silestone) from breaking or being damaged if the load shifts during transport. The racks may have wooden planks (fixed to them with adhesive tape, for instance) on the metal parts to prevent the slabs from coming into direct contact with them.
In the case of larger beds (12.6m), the first rack will be placed on the first differential, above the fifth wheel, and approximately 1.7m from the internal wall of the trailer. The second rack will be placed on the three rear axles. They will both be placed in the central part of the trailer and aligned with each other. To that end, the operator can use a tape measure and/or the trailer frame.
IN ALL CASES, EACH PART OF THE RACK WILL HAVE WOODEN CHOCKS FOR SUPPORTING THE SLABS ON ITS BASE.
Two chains with tensioners or slings will be placed at each end of the rack to secure the load, as shown in the photo.
The truck will be loaded with the bridge crane, always starting with the rack nearest the cabin and ending with the rack at the rear (to facilitate access to the trailer at all times).
Before placing the first package on each rack, it will be necessary to check that the rack components are properly aligned. To do this, the package will be placed parallel to the rack and deposited on it –still in the sling–, checking that its entire contact surface is correctly supported (base and sides). Otherwise the load will be gently lifted again and the parts of the rack that were not correctly positioned will be repositioned.
IMPORTANT! It is essential to control the load at all times, and not stand in a place where the load might fall, and prevent others from doing so. Always remain at a safe distance.
After depositing each slab package, wooden dividers will be inserted with a dual purpose, to facilitate the removal of the slings (*) and to facilitate their unloading afterwards.
(*) The slings will be removed through the sides, and the operator must NEVER stand in front of the package. If it is not possible to remove them completely due to their being caught between slabs, the operator will stand to one side of the rack (outside the area where the slabs could fall) and gently lift the crane to release the slings.
After loading the racks, the load will be secured using chains or ratchet straps. The chains will be passed over the slabs on the rack crosswise, preventing them from becoming knotted or twisted. The tensioners will be hooked by hand as tightly as possible, placing wooden stakes below each hook to tighten them without damaging the slabs. When tightening, a rigid metal rod will be used to tighten them more strongly.
IMPORTANT! Check the tensioners before use: they must not be rusted, the threads will be well defined, the hooks will be the appropriate ones and they will not have any deformations that could impair their efficacy. Before using a new tensioner for the first time, grease it. Otherwise it will almost certainly slacken, however strongly it was tightened.
BEFORE TIGHTENING THE LOAD ON THE RACK
Bear in mind that the chain must not touch the top of any slab (if chains are used). If this occurs, accommodate the first slab (on which it is resting): this slab will ALWAYS be higher than the others and if it not lowered slightly, this could give rise to poor tensioning of the chains and the load could shift during transport, causing serious problems. Normally this task is carried out by the driver and must be done using a lever.
We know that the first slabs will not be a problem when, after being tensioned, the chain is above them, without touching them. Final result:
12.b. High beds (closed – rigid or with canvas)
These trailers have a length of about 13.6m (three or four axles). They are characterised by their decks, formed by wooden planks made from Finnish phenolic veneer plywood. With these trailers, racks with wooden bases or racks made completely of metal can be used and they will be loaded with a bridge crane.
In these trucks, it is not necessary to secure the rack to the trailer decks but it is advisable to insert non-slip material in exposed areas of the frame that are in contact with the racks, such as cardboard or foam rubber strips.
To load these trailers, the procedure is the one described above:
Once the truck is in place and immobilised, the rear doors will be opened (securing them to the truck frame to prevent them from closing) and the stepladder will be put in place so that the trailer can easily be accessed. After positioning the racks as indicated for the low bed trucks of a larger size (in other words, the first rack on the first differential and the next on the rear axles), they will be loaded, with the only exception being that the slab packs must be inserted through the rear part of the trailer (otherwise, it would be dangerous, as the load would be very tall and the consequences in the event of an accident would be much worse).
The operator must ensure that the driver has removed the top crosspiece of the trailing structure and moved the entire canvas forward before starting to load.
The beam must be secured to prevent accidents (make sure the canvas sheet at the top has already been moved).
The racks are seen, centred on the axles. Placing the load in the trailer.
When the racks are loaded, the load will be secured using the chains. The chains will be passed over the slabs on the rack, taking into account the same safety criteria commented on earlier (crosswise, preventing them from becoming knotted and twisted and tensioning the chains by hand as tightly as possible with the wooden stakes– and then tightened using a rigid metal rod (to tighten them even more strongly).
12.c. Platforms
These trailers have a length that varies from approximately 2.9m to 12.6m. Their width is around 2.5m.
Normally, smaller platforms have front and back walls to facilitate their storage on ships. Those with longer lengths are completely open.
In the same way as with high beds, their decks are made from Finnish phenolic veneer plywood. They will be loaded using the bridge crane.
They are loaded as described above, and it is not necessary to fix the rack to the trailer deck, but it is advisable to insert non-slip material in exposed areas of the frame that come into contact with the racks. The same considerations as those indicated above also apply.
With respect to small platforms, the rack will be placed so that the load is centred on the rear axles. With larger platforms, the racks will be placed so that once loaded, the ends of the slabs are at the edge of the platform (see attached photos).
Placing of front rack (on the axle).
Centring of racks on the frame.
Final state of the front load (at the edge of the trailer)
Placing of rear rack (on the axles).
Repositioning part of the rack before finally depositing the load (to ensure its correct seating).
Rear load (also at the edge of the trailer)
12.d. Containers
In this case, the bed length is around 6m (larger ones exist, but they do not apply to our case), and it is on the truck frame.
As in the case of high beds and platforms, their decks are made from Finnish phenolic veneer plywood and so metal racks will be used, nailed to the deck.
They will be loaded with a counterbalanced forklift and three auxiliary loading operators.
The truck must be correctly positioned and immobilised. In this case, the truck will be placed so that the container is inside the loading warehouse, leaving sufficient operating space for the forklift (the truck cabin may be outside the warehouse). Once the above criteria have been met, the rear doors will be opened and the stepladder will be put in place so that the trailer can easily be accessed.
The stepladder will be properly placed to allow the operators to climb into and out of the truck without any problems.
Positioning of racks: the containers will contain only one rack, which must be placed as close as possible to the base of the container (1.85m from the base of the container and 1.18m from the wall). As in the above cases, the ends will be approximately 1.5m from each other, and when possible, three pieces will be put in place. The racks will be nailed to the deck and they will have a wooden plank at the base (to prevent contact with the metal structure in that area) and the sides will be clad with foam rubber clamps.
To put the trailer in the correct position, the operator can use a tape measure or the trailer structure itself.
Preparation of the inside of the container.
Distance from the top end of the rack to the side wall: approximately 1.10 m on each side.
Distance of the rack from the base of the container: 1.85m or (using the container design) 7.5 folds from the main beam of the base.
Cladding the vertical supports with foam rubber.
Lining the vertical supports with foam.
Final result: the chains or slings are hung to facilitate the securing of the load when the container is full.
IMPORTANT! The wooden planks placed on the external parts of the rack are nailed to the deck, to guarantee the rack is well secured.
Two chains with tensioners or slings will be placed at each end of the rack to secure the load afterwards. They must hang from the U-shaped inner rings for grasping once the loading operation has been completed. For this purpose, the operator can use tensioners (on one side) and hooks (on the other side).
See the photo:
Chains hooked by tensioners.
Same chains fastened with hooks at the other end.
Distance from the easel to the bottom of the container: 1.85m or (using the container design) 7.5 folds from the bottom master beam.
Nailing the easel pieces to the ground.
The truck will be loaded using a forklift fitted with an extensible fork for loads (photo 1) that has duly approved pressure clamps at the end (photo 2).
It is very important to mark off the work area, to prevent other workers from suffering accidents.
Mark off the forklift work area using chains.
To pick up the slabs with the clamps, separate them from the rest of the package on the loading rack, using the anti-tip bars on the racks. To do this, the auxiliary loading operator will separate the slabs using a reinforced metal spatula and help put the clamps in place when asked to by the forklift operator.
The number of slabs loaded simultaneously will always depend on:
a) The capacity of the clamps (see the validation on the rating plate).
b) The thickness of the slabs to be loaded.
c) The free space available inside the container.
Reinforced metal spatula.
Observe the position of the anti-tip bars and the position of the auxiliary loading operator at one side the package.
To separate the slabs, insert the edge of the spatula at one side. Do not separate more than two slabs at once.
After inserting the spatula, apply pressure on it.
The slabs can be pushed gently forward until they rest on the anti-tip bars.
Loading the container: when the forklift operator has correctly placed the clamp on the slabs to be picked up (as close as possible to the centre of them), the auxiliary loading operator will position it correctly and, as it ascends and moves, the auxiliary loading operator will accompany the load at all times, to prevent uncontrolled movements and reduce the likelihood of knocks to a minimum.
Putting the clamp in place.
Accompanying the load as it ascends.
IMPORTANT! Never stand beneath the load or the extensible arm, to avoid the possible falling of material or the breaking of the accessories. It is essential to control the load at all times.
There will be two loading assistants near the container (one inside and the other outside) to accommodate the load at all times, and prevent it from hitting the container walls or the other slabs (the slab could break them or it could also break, depending on the thickness and type of material). The rack will be completed on both sides simultaneously.
Securing the load: once the rack load has been completed, it will be secured using chains or textile slings (fastening elements). The fastening elements will be passed over the slabs on the rack crosswise, preventing them from becoming knotted or twisted. The tensioners will be hooked by hand as tightly as possible, placing wooden stakes below each hook (in the case of chains) to tighten them without damaging the slabs. When tightening, a rigid metal rod will be used to tighten them more strongly, or the ratchet tightening system will be used.
If, due to a lack of space, it is not possible to tension the fastening elements at one side of the load, the load will be fastened at the top.
Tensioning the fastening elements to remove knots or twists.
Tightening with the ratchet system.
Placing the wooden martyr under the tensioner. The two chains are tensioned simultaneously. When it is not possible to tighten more by hand, a rigid metal rod can be used.
Tensioned straps.
After completing and securing the load, if there is a large space between it and container wall, fill the space with a chock (a wooden one, for example) to prevent the load from becoming loose and falling off the rack, causing damage to people and/or property.
The chock will be custom-built, using nails and a hammer, wooden planks and other, smaller chocks.
Creating the chock inside the trailer.
Putting the chock in place: it must be fixed to the trailer using nails between the load and each wall with a hammer (by an auxiliary loading operator).