)PA pumps show up uell on Dutch Leylands
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Increased service life and reduction in first t have led to progressive adoption of :ributor-type injection pumps on Leyland ines in Dutch buses, in place of the origin-line pumps fitted. This was revealed last tk at Eastbourne, at the Southern Areas ference of CAV Ltd., where there was a ,arture from the traditional pattern this r. Instead of all the main speakers being I personnel, this year one of the papers 3 presented by a Dutch engineer, Mr. L. C. >pen, director of engineering, NV Centraal oherstelbedrijf (CAB) part of the Netheris State Railways organisation.
Ar. Koppen spoke about the operation of in Holland and the application of British ver units and equipment—exclusively Leyengines and CAV components. He exned that Netherlands Railways was a 'fed company with all the shares owned by Government and that, as a company, it 3 responsible only for running the railway tern in Holland. But under the railway brella, he explained, there were 22 bus npanies, with the railway owning a majorshareholding in 18. Each one of them was -governing and was expected to be comitive.
rhe common link between the bus corndes, said Mr. Koppen, was CAB, which :rated repair and overhaul workshops for 2,200-vehicle fleet and gave technical advice and information and, among other things, formulated_ designs for all the buses used throughout the group, Vehicle standardization had resulted in 1,400 vehicles in the fleet having Leyland engines and other units of the same make and Mr. Koppen said that the 0.600 units averaged 373,000 miles between overhauls, while the 0.680s averaged 435,000 miles.
It was clear from what he said that CAB placed considerable importance on checks to ensure correct lubrication, correct governed speed and correct filtration: the engine oilchange period was said to be 18,600 miles, with 224,000 miles the usual point for an injection-pump change.
CAB rebuilds about 250 engines a year, and Mr. Koppen gave details of a modification carried out on six 0.600 engines by the fitting of DPA distributor-type injection pumps in place of the in-line units which were the original equipment. The results of this modification were shown to have been remarkably good. Up to the end of 1968, pumps had covered up to 400,000 miles and in the case of pumps on two particular buses at one depot, only £11 10s had been spent on them in that time.
The first pumps are still running so it was not possible to say the exact service life, said Mr. Koppen, but because of the increased service life coupled to reduce first cost there had been the progressive installation of DPA pumps on Leyland-engined psv operated by Netherlands Railways, until 500 now have this type.
Results of a thorough inspection of one of the over-400,000-mile DPA pumps referred to by Mr. Koppen were covered in the second paper at the Conference which was given by Mr. F. T. Houchin, sales manager (home) of CAV. The stripped-down pump was exhibited at the Conference. Most parts were within manufacturing tolerances for the new component.
Mr. Houchin said that before the pump was stripped it was subjected to a full series of leakage and functional tests. There was some leakage from the throttle shaft but on the test the pump performed within the requirements of the test plan for new production pumps, except for a slightly-low transfer pressure.
The results of the rig tests were confirmed when the pump had been stripped down and it was found that there was wear on the pressure face of the end plate which was the cause of the low transfer pressure, and the throttle shaft was worn causing the leakage at this point. Apart from these two components, none of the parts in the pump was worn to any degree. Any modifications already in effect on the two parts in question would have improved the situation still further.
During a question-and-answer session, Mr. S. Barber said that since the merging of Simms with CAV, the range of injection pumps made by the two firms had been examined and that the existing ranges would continue to be marketed. Mr. Barber said that new designs of governors were under dovelopment which will meet the requirements for vehicle and industrial diesels for the next 10 years.