Portable bridges delivered by L&T give India’s defence forces the much-needed edge
Military engagements and natural calamities make it necessary to traverse quickly over inhospitable terrain. The challenging topography of most border areas makes it necessary to have a reliable portable solution.
L&T Defence, had in 2019, received an order from BEML Ltd for the mass production of 110 Sarvatra bridging systems. Sarvatra is a Tatra-truck-mounted, mechanically-launched, multi-span, mobile bridging system.
Developed by the Defence Research & Development Organisation (DRDO), Sarvatra can be launched in just 100 minutes and it can connect gaps ranging from 15-75 metres providing a 4-metre-wide fully decked roadway for traffic, including heavy military vehicles.
The bridging system consists of a Tatra vehicle, bridge superstructure, launching mechanism and hydraulic systems. L&T was assigned to produce bridges and launching mechanisms made up of RDE-40M aluminium alloy and S690QL material, respectively.
L&T Defence began manufacturing the bridging system at its state-of-the-art manufacturing facilities housed in the AM Naik Heavy Engineering Complex at Hazira in Gujarat and the Strategic Systems Complex at Talegaon near Pune. The team braced itself to deliver the systems well within the timelines.
Speaking of the best-laid plans of mice and men, no sooner was the project initiated than the COVID pandemic slammed in, throwing a spanner in the works. The supply chain and skilled manpower availability were affected. This led to several delays and frequent stoppages of work.
Besides, several other factors led to initial high cycle time – such as handling of unique material and facility development.
To compensate for the lost time, the project team increased its vendor base and spread the pre-fabrication activities across various locations. In-house facilities were developed to ensure on-time full-kit availability.
Innovations at Work
As it is highly prone to developing cracks, the fabrication of aluminium-grade RDE 40M was a critical but essential process in the project.
L&T Defence set up environmentally controlled enclosures for material storage, fabrication and welding. This facilitated a dust-free environment essential to achieve best quality weld.
Furthermore, to enhance the weld kg deposition and eliminate defects, the project team made use of robotic systems. They designed innovative fixtures to control distortion and achieve the required dimensions within the tolerances specified.
To utilise the hinge boring machine fully and achieve the required throughput, the team set up two stations for line-boring of 35mm hinge holes with an accuracy level of 50 microns.
Thanks to a slew of other steps: such as tackles welding, use of lofted drawings, spreading of assemblies across all the Defence shops, the addition of an assembly line and the implementation of the multi-station concept, the bridge output increased from four to 10 per month.
Creative thinking and continuous development contributed to the improvement of the cycle time for the superstructure by 54% and for the launching mechanism by 46% as compared to the initial time.
The entire order was delivered to BEML by March 2022, yet again affirming L&T’s reputation for timely delivery of critical projects.
