DESIGN DEVELOPMENT OF AN INDIGENOUS TRICYCLE RICKSHAW
Phase 6: Planning for consumption Step 1: Design for maintenance
4.3 Planning for retirement
Environmentally safe disposal of a product that has completed its useful service life is becoming mandatory both on the part of the manufacturer as well as the consumer/ user in the view of growing threat to the global environment (Otto and Wood, 2001) and became 4th phase in the production - consumption cycle of a product development. For sustainable development, recycle of various materials from a retired product is another essential factor. The forth process in the production-consumption cycle (Fig. 3.39, p 85, Chapter 3, Section 3.5.1) is essentially regarding the disposal of the retired product and also forms the seventh phase (Chapter 3, Flow Chart 3.1, p 83) in the morphology of design process (Chitale and Gupta, 1999). Any consumer item can retire because of either physical deterioration or due to technical obsolescence. Much cannot be done about technical obsolescence but efforts can be made about reducing physical deterioration. In order not to incur extra cost providing longer than useful life, the product should be designed to wear out physically at the same time that it becomes technically obsolete (Chitale and Gupta, 1999). A complete compromise between obsolescence and wear out is generally not possible, because the elements of design that contribute to a Fig. 4.3 FRP wastes generated
from components as side trimmings
Fig. 4.4 FRP wastes
placed inside mould Fig. 4.5 FRP wastes inside mould impregnated with resin and hydraulically compressed
Fig. 4.6 FRP battens moulded by Recycling wastes
Fig. 4.7 Floor panels (shown above) and passengers’ seat (not shown here) fabricated in FRP for Dipbahan+ required
reinforcement. Wooden battens were used prior to FRP battens using FRP wastes was available
Fig. 4.8 Floor panels and
passengers’ seat fabricated later in FRP for Dipbahan+ are reinforced using FRP battens moulded from FRP wastes instead of wooden battens used earlier
longer life of a product are also essential to ensure adequate reliability and maintenance (Priest and Sanchez, 2001).
The question is - what determines as to when an economic commodity in use such as a tricycle rickshaw has reached a stage at which it should be retired? It can be safely assumed that when the article in use is worn to the point at which it is incapable to render adequate service any more, and then the need for replacement is clear. However, the fast pace of technology accelerates the aging process of goods in use. At present times goods in use are retired more frequently because of technical obsolescence rather than for physical deterioration.
To the product designer, the question whether to design to prevent physical deterioration or technical obsolescence is of fundamental importance. A tricycle rickshaw being a Human Powered Vehicle of mass appeal, functionally useful, with very low cost of ownership, existing for more than a century without much changes in its form and function can not be wiped off by technical obsolescence so easily. Thus, designing to overcome physical deterioration played more dominant role in design of the Dipbahan.
The impact on a new design of tricycle rickshaw is more immediate as an old structure or system must be replaced by a new one with minimum disruption of normal operations, specifically concerning the early retirement of a traditional rickshaw. The structure of traditional rickshaw is totally craft based and uses many different materials. Most of these get deteriorated over a very short period of time. Only the mild steel based components that are sourced from bicycle and tricycle component industry are of some use. Even the chassis of traditional rickshaw is normally fabricated out of scrape materials and is also a non-standardised item. Therefore it can be assumed that in the longer run, the Dipbahan range of newly designed tricycle rickshaws with long lasting and easy to replace components assembly can successfully replace the traditional version of the rickshaws in market.
The values that are available when a product reaches a terminal point of service and influence of these values on design is the concern of the retirement phase in design. The purpose of this phase is to take into account the problems associated with retiring and disposing of a product. Designing for retirement, according to Asimow, must consider the following aspects (Chitale and Gupta, 1999):
4.3.1 Designing to reduce the rate of obsolescence by taking into account the anticipated effects of technical developments.
Tricycle rickshaw has been in existence for a long time. Due to its localised and decentralised manufacture and very low margin of profit for its manufacture associated with common people’s perception of rickshaw, not much technological developments are initiated that can create obsolescence of traditional tricycle rickshaw. However, during design development of Dipbahan+, due consideration was given to reduce the rate of obsolescence by taking into account the anticipated effect of technical developments in
near future. One such consideration is introduction of FRP. Since wood and other natural materials are becoming scarce and expensive, these may render traditional rickshaw design obsolete. To counter this aspect, Dipbahan+ has been furbished with FRP component extensively. Another aspect in case of Dipbahan+ was its new design, materials and processes that are used for its manufacture. As stated in Chapter 3, p108, design of Dipbahan require speedier implementation. This was to counterbalance the technological change. Retrospectively this was proved right by the number of efforts initiated by various persons and agencies in designing and including copying the Dipbahan versions after its tremendous success in the market. When prototype of Dipbahan was previewed by selective persons, it was commented that the design and its material and manufacturing process is excellent and this should be immediately introduced in the market to cater to the needs of the users. Also with each passing days, people who do not uses rickshaw but automobiles were trying to ban this mode of eco- friendly transport from the cities. Thus further delay in implementation could have adverse effect on the future of the project. Political situation required more and more income generation projects with lower capital costs to solve unemployment problem and it was an opportunity to introduce Dipbahan immediately to reap that benefit.
Entire structure of the Dipbahan+ has been designed in such way that if desired, it can be easily converted into an electric tricycle rickshaw by easily fitting it with electric motor, solar photo-voltaic panels and storage battery. The basic assumption in converting the Dipbahan+ to electrically operated one is that it will retain its pedaling option as it is and it will be only added electrical motor and other paraphernalia like battery pack, battery charger, controller etc. to the vehicle. Thus to convert Dipbahan+ to an electric one using motor required few considerations mentioned below:
• There should be space for housing the 2 battery pack with overall dimension of 400 mm X 200 mm X 250 mm (Length x Breadth X Depth).
• The chassis should be able to support fixtures for fitting the motor below the floor panels and also the overall weight increase of approximately 60 Kg.
• The motor controller actuator should be positioned at handle bar to be easily operated.
• Charging socket along with battery charger should be located within the frame that can be plugged to external charging system, normally 220 Volt AC or through photovoltaic solar panels.
To facilitate conversion of Dipbahan+ to an electrically operated vehicle, its chassis has been designed to bear additional load of battery pack, controller, charger system and motor. It is designed to facilitate electric motor to be coupled to rotate the rear shaft through pulley and V- belt with built in gear reduction. This will facilitate retaining the same wheels from the Dipbahan+. Currently hub mounted electric motors are being used in electric 2 wheelers and if this is used will require change of wheels. These are also expensive. Using stand alone motors to rotate the rear axle will also simplify the design
and motor mounting can be easily located below the floor. Part of the luggage space below the passengers’ seat can be used to house the battery pack, charger and motor controller by providing additional depth to the rear floor panel. Also motor controller actuator can be easily mounted on the handle bar.
Dipbahan+ has been designed to accommodate all these components in spite of retaining all its advantages and these features are not easily visible.
Facilitating the above in the Dipbahan+ did not have any significant impact its existing design. Chassis was anyway designed to take care of overloading than the normal payload. Presently entire space below the seat has been provided as luggage space and it is seen that this space is not always used by all passengers. Thus partial reduction in luggage space will not have adverse impact. There will be definite increase in weight in case of electrification, but this will only affect the rickshaw puller once he is forced to pedal it due to discharge of the battery pack. Also additional weight is maximum of 60 Kg.
Similarly, it can be fitted with a small fuel engine to convert Dipbahan+. to a motorised tricycle rickshaw.
The above measures ensure that the newly designed rickshaw will have lower rate of obsolescence considering anticipated technological developments.
4.3.2 Designing physical life to match anticipated service life
As discussed in section 4.2.7 of this chapter, p 119 the newly designed tricycle rickshaw has been designed for a minimum physical life of 7 years in reality. However parts that wear out during normal operation will require replacements. These are tyres and tubes, sprockets and chains, brake pads, foot pedal rubbers etc. Dipbahan+ has been designed for an anticipated life of 7 years to be attractive for the rickshaw pullers to own one.
Considering the capital cost of the Dipbahan+ is Rs. 13,500.00, a useful life of 5 years as considered by the licensing and insurance authorities will entail a depreciation of Rs.
2,700.00 per year @20% per year in straight line depreciation method. This comes to Rs. 9.00 per working day provided, rickshaw pullers use it for 300 days a year. If the rickshaw puller repays his loan over 2 years i.e. 600 working days @ 300 working days per year and rate of interest 12 % per annum calculated over reducing balance, his repayment installment comes to almost Rs. 25.00 per working day. Thus for the first two years, his daily outflow will be Rs. (25.00 + 9.00)= Rs. 34.00 per day, assuming rickshaw puller will set aside Rs. 9.00 per day as depreciation and also for the next 3 years, he will require to set aside Rs. 9.00 per working day so that he can buy a new Dipbahan at the end of 5 years. Here his old Dipbahan+ will be of zero book value. In the above calculation, interest in the set aside amount as depreciation was not considered as well as any increase in the cost price of Dipbahan+ after 5 years. There will be also some residual value for the old Dipbahan+.
Once we consider the useful anticipated life of 7 years, and depreciation is spread uniformly over these years, annual depreciation comes approximately 15% per annum
and the set aside amount becomes Rs. 7.20 per working day. This is 20% lower that the earlier and the rickshaw puller can operate the Dipbahan+ for 2 more years. However, the Municipal councils and corporations have to agree to extent the license to 7 years. In this case there is a match between the physical life and anticipated service life.
It is assumed that once Dipbahan+ currently on road lasts more than 5 years, authorities can be convinced, since there are valid documents to convince them. These includes, license issued earlier, loan and membership document, insurance documents etc.
4.3.3 Designing for multi-levels of use to facilitate adaptability for further use with a less demanding level after the service life of the product at higher level of use is terminated
In case of a tricycle rickshaw, satisfying the above guide line is difficult if not impossible.
However when the tricycle rickshaw is no more suitable for transporting passengers, by removing the passenger seat, it can be used for transporting goods, poultry products etc.
4.3.4 Designing the product to facilitate recovery of reusable materials and long-lasting components. Introduction of modularity in design instead of integrated designs.
The tricycle rickshaw designed uses various mild steel elements in chassis and various parts and components; rubber materials in tyres and tubes; glass and plastic in rear view mirrors; plastics in rain guards and fibre glass reinforced plastic components in seat, hood, floor panel, rear panel, side panel, rear mud guards. Mild steel materials specifically rear axle can be reused and design of the tricycle rickshaw facilitate its recovery for reuse. Other mild steel materials can be reused based on their condition.
Otherwise these can be recovered for recycling easily. Rubber tyres are not reusable after the expiry of its service life. Fibre glass reinforced plastic components based on their condition can be reused and design facilitate their recovery. If these are not in working conditions, these are to be discarded in land fills. However, a process has been developed in house at Department of Design, IIT Guwahati to reuse the FRP components as refill in new component making (Section 4.2.9, Fig. 4.3 - 4.8, p 121).
Second aspect of tricycle rickshaw design is introduction of modularity. From the beginning of the research work, emphasis was on introduction of modularity. Thus after Dipbahan was introduced as a passenger version, two more version based on the same platform was designed and fabricated through participation of Small Enterprise. These are Dipbahan Ankur as school van and Dipbahan Pariskar as a municipality solid waste disposal vehicle for collection and disposal of garbage from individual households, where on the basic chassis frame the passenger seat component may easily be replaced with modules of specific requirement (which is detailed out in Chapter 7).
4.3.5 Examining and testing of service-terminated products to obtain useful design information
Service terminated products were collected and examined to ascertain the cause of its failure thereby shortcomings of design and materials. This provided some vital information for redesign of the newly designed tricycle rickshaw. One such case in hand was rear wheel bearing and bearing block. It was found that the rear wheel bearings used to get damaged frequently. There were also few cases of breakage of bearing block during operation of the rickshaw. The causes for these were traced to:
i. Breakage of bearing is due to lack of oiling and greasing. This itself is to be attributed to difficulty in oiling and greasing by the rickshaw pullers. The bearing block used is designed to protect the bearing from dirt and dust by enclosing it (Fig. 5.33, p165). The axle comes out through the opening at both sides of the bearing block. Therefore for oiling and greasing require dismantling the bearing block. Normal rickshaw puller as well as mechanics in rickshaw repairing shop are not habituated at this. For oiling and greasing, mechanics charge higher amount. Every time it amounts around Rs. 20.00 – 25.00. But with traditional foot pedaled tricycle rickshaw with locally fabricated bearing bracket keep the bearing exposed (Fig. 5.32, p 165) and this assist in frequent oiling and greasing without dismantling anything and hence more convenient. This prevented the damage and failure of the bearings. This has been incorporated in the new design.
ii. Second aspect of breakage of bearing block was due to absence of a rubber piece used as dampener between the bearing and the bearing block and a wooden piece between the chassis bracket and the bearing block used for mounting the bearing block to the chassis. Thus being a cast iron piece, during sudden shock on road, the bearing block used to crack. It was also found that in a few cases, bearing block itself was sub-standard. Usage of mild steel bracket in the new design increases the life of the component.