The standard equipment for normal hydraulic wall saws are sufficiently known. In the cases of small jobs it is often too laborious to carry the complete sawing equipment to the building site. Equally the necessary modification work requires often very high labour costs. Obviously the simplest solution in these cases would be to buy suitable machines or equipment. It doesn't help the contractor, however, if he invests in new and expensive machinery if they are not fully used. Therefore our company follows the principle to build our machines and modify them with additional components in such a manner, that they can be used more effectively.

   Sawing of wall openings

The machine assembled from existing parts, as can be seen in the picture, was first used at a site of HEW (Hamburg Electricity Works). In the electrical load distribution centre two wall openings were required. The load distribution centre is a sensitive security area, which is manned by HEW staff round the clock. In this area the loading of the power stations surrounding Hamburg is constantly monitored. In case over an excessive demand in electricity supply additional electricity is connected, in other words purchased, from France or other European countries. In the other case of over capacity electricity in fed into the European grid, in other words sold. This job demands a high level of concentration. Therefore a demolition technique with a minimum noise level was required. The 30 cm (12 in) thick wall could have sawn with a wall saw. After viewing a video the customer decided to use the low noise wire saw technology. The openings in the reinforced concrete wall were 1,20 metres (4 ft) wide, 2,30 metres (8 ft) high and, as mentioned before, 30 cm (12 in) thick. The job was carried out smoothly to the full satisfaction of the customer.
 

      Wire saw for circular openings

During a meeting on a building site I told the Technical Manager of a well known construction company in Hamburg, Theo Urbach GmbH & Co. KG, that we are planning an equipment, with which circular holes of almost unlimited size could be cut into brickwork and reinforced concrete walls. We immediately received the order to cut a 2,70 metre (9 ft) diameter hole for a circular stair case into the top floor ceiling of the Hamburger Sparkasse (Hamburg Co-operative Bank) in the Eidelstedt, a suburb of Hamburg. This gave us an incentive to build the equipment as quickly as possible. As additional parts we used standard components from the steel trade. Amongst other things we needed a square tube, 180 x 180 mm (7 x 7 in), 3 metres (10 ft) long and two square tubes of 150 x 150 mm (6 x 6 in) and 1, 50 metres (5 ft) long. In addition some M16 thread rods and some U-shaped bars 4 mm (3/16 in) thick and 50 mm (2 in) wide. All these parts were cut to size and necessary holes drilled in our workshop. The special base was welded together. Due to the tight time scheduled a radial feeding systems was initially left out. After a satisfactory test run the individual pieces were brought to the rooftop of the Sparkasse by means of a building site lift. At a point specified by the customer for the centre axis of the cut-out our operators drilled a hole of 211 mm (8¼ in) diameter into the 44 cm (17 in) thick ceiling. Now the equipment was assembled. The 180 x 180 mm (7 x 7 in) square tube was fixed vertically into the hole. At top and bottom the 150 x 150 mm (6 x 6 in) square tube was attached at a 90 degree angle. At the end two small guide rolls were assembled. The upper guide roll secured the radius of 1350 mm (4½ ft) the lower one secured the necessary downforce of the diamond wire onto the concrete. The base of the drilling unit and the drilling unit itself with hydraulic motor and drive pulley was mounted at the upper square tube. The wire was fed through a 12 mm (½ in) hole on the radius line. A building rack secured the support. The part to be cut our has a circumference of 8.48 meters (28 ft). As it was a ripped structure of the ceiling the average thickness was 370 mm (15 in) and the total area sawn 3.14 square metres (34 sq. ft) including 430 sq. centimetres (67 sq. in) of reinforcement bars. After completion of wire sae operation and the dismantling of the machine three holes of 70 mm (2¾ in) each were drilled at a spacing of 120 degrees at a radius of 900 mm (3 ft). The removal followed the following day with a 70 ton crane ordered from Messrs. Alex Grund. The distance between the pivotal point of the crane to the middle of the concrete core was 26 metres (85 ft). The concrete core had a weight of 4.5 tonnes. At these parameters we were reaching the maximum capacity of the crane. The circular concrete core was fixed to steel cables fed through the 3 holes, lifted and dumped into a container. Immediately afterwards the spiral stair case could be built into the 2.70 metres (9 ft) wide opening.

Jeannot Draeger