New product development is essential for business growth. The costs, however, can be crippling as Rolls Royce found out in the early 1970s when simultaneously running two major engine development programmes – the Olympus and RB211. The lesson is clear: cost control is vital and, most of all, the time from concept to commercial exploitation should be compressed to ensure new product development yields positive revenues quickly.

So much for theory. In practice there are always problems. Call them challenges if you like, but the danger is that the route to the final product becomes so twisted that the original objectives are forgotten and pots of money are poured into exploring unworkable solutions. In developing their ZX range of hoists for the international market Street Crane worked to avoid these pitfalls – with some success and a few hiccups.


To take on the international export trade the UK manufacturer required a family of new hoists, in the mainstream zero to 25t range. These needed to be designed and certified to UK and international standards. Modular design, inherent safety, low maintenance and ease of customisation were identified as essential characteristics. These parameters were validated and refined by research with both UK and overseas customers.

Time was a critical factor. A decision was therefore taken to use CAD technology to speed the design process. A successful application for a government research and development grant provided £130,000 ($210,000) pump priming funding for what eventually became an £850,000 ($1.4m) programme.

Development programme

Traditional engineering development is a cyclical process of design, calculation, prototyping, testing and refinement. Several iterations are usually required to achieve a workable product and only then can it be field tested and exposed to the ordeals of the real world. Often, further modifications are needed before the product is brought to market.

During the pre-development phase, analysis of service records gave useful insights into common causes of failure in the field. These could be due to various problems of design, materials, manufacture, unsuitability for the particular duty, or simply misuse. Valuable insights were obtained as to which components were weak links and the need to compensate for the in-service abuse of equipment.

The aim was to produce a competitive and reliable product while reducing the number of development cycles and so keeping within budget. Virtual engineering using CAD modelling was identified as one method whereby the physical attributes of components, sub assemblies and whole products could be explored easily, quickly and at low cost.

Using Cosmos software from the USA, virtual models were created at component level and subjected to varying degrees of stress. Mathcad software was also used to allow sequences of “what if” calculations to be explored and a DU436 stress calculation package enabled gear designs to be optimised. Working drawings for production and CNC programs for manufacture could be produced directly from the system. Solid Edge 3D CAD software was used as a primary design tool enabling interactive component design from Excel spreadsheets. This programme allowed drawings to be produced automatically and allowed scaling of components to produce families of components of differing size with the same design characteristics.

Technology trauma

There is no gain without pain. This is certainly true in the adoption of new forms of technology that need to be validated against proven manual systems. The installation of computer-based modelling and calculation, therefore, initially had a negative impact on design productivity. This was because of the need to duplicate all calculations until the new programs could be fine tuned and their predictions treated with confidence.

The efficient linking of technology was one area of difficulty. Inevitably every company has an existing investment in hardware, software and training and new systems need to be grafted onto this rootstock.

The first 3D modelling system that was tried proved adequate for design and calculations, but had serious difficulty interfacing with the existing Novell-based network that runs the other company systems. This made it difficult to transfer data from the design to production departments to produce drawings, CNC programs for manufacture and purchase order details for raw material and so on. These problems were eventually overcome with the installation of Cosmos software so that the benefits of integrating design and manufacturing processes could be fully realised.

Testing, Testing…

Before any hoist can enter service its performance must be tested and certified in accordance with both UK and international standards. These include BS466, BS2573, as well as relevant codes from FEM, ISO and DIN. All these standards try to replicate normal patterns of use. Each hoist must lift and lower continuously for a prescribed number of cycles reflecting the ‘M’ classification so that work equivalent to 20 years of operation is compressed into a few months.

Unlike real life, where typically only 60% of lifts are at full load, the standards require that all trial lifts are at full safe working load. As a matter of course, Street tested all prototypes to 150% – half again beyond the cycles prescribed in the standards to ensure a greater factor of safety and reliability.

Some fairly subtle techniques are used to evaluate performance during testing. Monitoring motor power for example provides a guide to the overall efficiency of the drive train. Typically a hoist consumes more power when it is new, but power consumption falls and flattens as components bed in and become work hardened. A sudden rise in power consumption highlights a problem, and this happened when a bought-in oil seal developed faults. The seal was subsequently changed, the test restarted, and the critical point passed without further problem.

At component level there are some items that must be tested to destruction. Rope anchors, for example, are tested to their ultimate limits to gain confidence in their field performance. Components that are irregularly shaped, where there is a possible mis-fit between the predicted performance that is calculated and real life, must similarly be taken to destruction.

The mechanical trials produced a wealth of data from which service schedules could be drawn up. In some cases potential service difficulties in the field were identified. These included issues such as component access. An operation that appears simple on a workbench may be far more difficult when units are installed at high level. This feedback was used to rework the design to improve access and serviceability.

The current round of development began in January 1996. In March 1997 a new dedicated hoist works was opened and the first products were released in August 1997. Currently ZX hoists are available up to 10t with further hoist models at various stages of design and development. A full family of hoists covering the target zero to 25t range will be available by September 1999.


The new hoists have been customer trialed in the UK market and have proven both popular and reliable. Street has established project partnerships with indigenous crane builders in Europe, the Far East, Australia and New Zealand. A wholly owned subsidiary operates in South Africa. In many cases these sales outlets use Street’s design software that enables them to produce structural components locally and select the correct hoists, carriages and controls for order from the UK.

The availability of the ZX has added a new element to these relationships. The modularity of the design makes it possible for the end user to specify a hoist that is as simple or sophisticated as the application demands. Drive systems and gear boxes can be mixed and matched to provide the ideal combination. The basic workhorse can also be customised with accessories such as soft start speed control, condition monitoring, brake wear indicators, secondary brakes and so on. Modular design means an overseas agent can build hoists to order. This is helpful because less capital is tied up and inventory turns over more rapidly.

During 1998 Street has used the flexibility and competitiveness of the new generation of hoists to gain a foothold in the North American market (HOIST issue 3, p2). Here there are many midsize crane builders with fabrication expertise but who are reliant for mechanical components on the very multinationals who are their direct competitors. The facility to source hoist technology from a company that is not a direct competitor is appreciated.

Lessons learned

Street Crane says that its experience has shown that technology is a great leveller. It can enable a producer of modest size in international terms to initiate and complete a major new product development programme in a fraction of the time required by conventional methods. No development process is easy and new technology is far from being the plug-and-play, shrink-wrapped solution that it is hyped up to be, Street has learned from first-hand experience.

Testing is, and always will be, vital. Ideally these tests must replicate real life, and reflect the fact that many users will overuse and abuse equipment. Nevertheless, the company reckons that the venture was worthwhile and regards the time, effort and money that went into new product development as an investment that will support its plans for global development.