News: Remanufacturing as a cost-effective option
Remanufactured transmissions enable off-highway operators to get the most from their assets says Mike Goatley, Of ZF's Off-Highway Division.
Monday, 27th October 2008
Engineering Talk reports that, for companies seeking to gain maximum utility from their mobile assets, remanufacture of transmissions is a proven way of extending asset life considerably. In addition, the updates that can be implemented during the remanufacturing operation mean that the transmission is often more efficient, flexible, and offers more facilities than previously. To markets brought up on repairs, remanufacture is something new - and suggests higher cost. This is true: remanufacture is more comprehensive in its scope, and is therefore more expensive than repair. However, cost is relative; if a fleet of trucks is standing idle because of one transmission failure, then the cost of refurbishing the transmission against that of the lost productive time of the vehicles is minimal. Of course, repairs are something that we are all used to and are comfortable with; but if we stop for a moment to consider the narrow definition of the word, then we can appreciate why more and more fleet operators are adopting remanufacture instead. Repair generally means rectifying that part, or parts, which have gone wrong. In the field under pressurised working conditions, this means quick replacement of components that have failed. However, this takes no account of what caused the failure initially. Consequently, a failure may be rectified with a repair, only for it to occur again due to the original cause not being identified and put right. It doesn't have to be this way; ZF transmissions, as employed on cranes and wheel loaders and backhoes, are equipped with electronic black boxes, both to optimise transmission operation and record operational data. The TCU, as it is called, is provided with an error memory, which enables it to record faults occurring on the transmission system. This means that when a transmission failure happens, the TCU records the cause of the fault; and when the transmission is removed subsequently this data is retrieved, which means that not only the failure is identified, but also its not- so- obvious cause. As a result, a more comprehensive refurbishment regime can be applied to ensure both problems are eliminated. Experience gained from using recording and analysing fault data in this way has convinced ZF that the remanufacture process is far more comprehensive and offers greater benefits to the off highway vehicle operator than simple repair. This message has already been heeded by a number of major off-highway manufacturers, who ship failed transmissions directly back to ZF and receive fully remanufactured and tested ones in their place. The major benefit of this procedure is that it reduces the overall time the off-highway vehicle is standing idle and is far more cost efficient overall for the vehicle operator. compared with a new aftermarket transmission, remanufacture is only a third to half of the cost; a saving that can make manufacturers, who are facing long lead times for new equipment, review their options. The process of remanufacture entails a unit being fully stripped to component level; all parts are then cleaned and inspected to factory standards, and any parts that need replacing are genuine parts to OEM standards. New bearings and any product updates or improvements are also included in the remanufacturing programme. Units are reassembled to OEM standards and then fully load tested by ZF to ensure that they function in accordance with factory specifications. Remanufacture offers the user many safeguards: first a TQM programme run by ZF ensures that the job is always done "right first time". Secondly, remanufacture addresses the critical issue of genuine parts. To many operators the policy of using nonstandard parts in repairs is acceptable due to cost savings; however, the policy is flawed because many nongenuine parts are designed using reverse engineering. This is because manufacturers of such components do not have access to original designs. As a result of this process many nongenuine parts are designed and manufactured from inferior materials, and with poor tolerances. In contrast, when ZF designs and manufactures a transmission, the parts that are used provide a synergy of operation - all of them play their part in the overall calculated life of the transmission. If, in the event of a failure, cheaper nongenuine parts are used in the transmission, then this operating synergy is lost and the vehicle operator has no warranty to fall back on. The third remanufacturing safeguard is safety. If operators are using parts not recommended by the manufacturer, then they could find themselves in trouble if for some reason an accident occurs, and those parts are highlighted in any subsequent investigation. The fourth safeguard is testing; repairs undertaken in the field cannot generally be tested; and the investment required for comprehensive in-house testing by nonmanufacturer repairers is usually beyond the scope of their resources. This is not the case with manufacturers such as ZF, where every remanufactured - and repaired - transmission unit is tested for up to six hours on one of ZF's purpose-built test rigs. Only then is it ready to be shipped back to the customer, complete with a ZF warranty. Job done then? Not quite. A while ago ZF asked the question of what happens when a remanufactured or repaired transmission is reinstalled. This resulted in the introduction of an optional service of installation check, to obviate any post installation problems. The service is designed to optimise shift quality and clutch life; it is crucial to perform on reinstallation of the transmission because of the requirement to ensure that the clutch fills at the optimum rate for smooth shifting. Also included in the service check are transmission mountings, propshafts, engine connections and the operation of any direct interlocks or other safety functions. In addition, the ZF engineer responsible for the service check also installs the latest updated software in the transmission control unit, ensuring the maximum in operating efficiency for the vehicle user.
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