1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156 
OLD ENGINES need never die, it would seem—provided spares are
Page 83
Page 84
Page 85
If you've noticed an error in this article please click here to report it so we can fix it.
obtainable! This is my impression following a visit to British Railways Engineering Ltd's Swindon Works, when a close look at the reconditioning methods employed convinced me that their high-grade workmanship pays off.
I discussed with technicians the problems of providing a reconditioning service enabling BUT automotive type 150/200 bhp diesel engines to propel rail cars 220,000 miles in two to three years between major overhauls. Their aim is to give an overall engine life of 20 years plus,—say, 14M miles.
In addition to the BUT diesels, reconditioning is applied to highly sophisticated turbocharged / intercooled loco engines of up to 1,750 bhp, to all manner of civil engineering equipment, to rolling stock running gear and to the repair of carriage bodywork including re-painting and so on.
As announced in CM, January 2, 1970, an engine reconditioning service is being offered to road-vehicle users by BR Engineering Works in Swindon, Derby and Glasgow. At Swindon 12 to 15 BUT diesels are overhauled in a working week and existing capacity could eater for the complete reconditioning of six to 10 vehicle engines a week together with the overhaul of two vehicle chassis. There is ample space and scope for expanding the engine and chassis service and as many as 20 vehicles could be accommodated at one time. The reconditioning of complete vehicles including bodywork could be arranged and contracts for major overhauls involving overtime or weekend working would be considered. Emergencies on the railways frequently necessitate overtime working in the shops.
In the short period that the service has been available engines have been reconditioned for City of Oxford Motor Services Ltd and Swindon Corporation, and specified repairs to chassis have been undertaken for these undertakings. And there have been many enquiries from other bus companies.
BR technicians are accustomed to tackling difficult jobs requiring an expert knowledge of engine design and metallurgy. And although the loco engines mentioned have an output of up to 10 times the power produced by the rail car units and operate at a far higher bmep, mention of some of the problems involved in keeping them running at peak efficiency is indicative of the valuable knowhow available. The diesels are Maybaeh units and the cost of reconditioning is normally in excess of X5,000.
One of the causes of heavy oil consumption was traced to an unsuitable bore finish and a honing pattern was eventually evolved that reduced consumption to an acceptable amount and was later applied beneficially to the BUT diesels.
It was also necessary to employ closer fitting tolerances in the case of certain Maybach components and a re-appraisal of critical tolerances in the BUT engines lead to fitting modifications that have contributed to the units' long life between major overhauls.
On a highly technical level, fatigue stress failures in the Maybath engines have necessitated the precise re-finishing of crankshaft fillet radii and of other components (including structural members) to remove "stress raisers" and applying a final polish to connecting rods.
It is perhaps significant that oilcooled pistons of the Maybach engines are of the type mentioned in the January Technitopics as an example of a form that could be developed for very high output road-vehicle diesels. Overcoming problems relating to these pistons and the fatigue failures has contributed to the store of knowledge of the technical staff regarding the effects of high thermal and
• mechanical stressing and is an example of expertise developed ht the refinement of a highly sophisticated diesel that could be extremely useful in the vehicle engine field generally. Of pertinent interest all BUT engines are now fitted with Wellworthy Alfin bonded-insert pistons, the use of which has substantially improved the service life of the top rings and reduced oil consumption-. Pre-boring the cylinders before installing the dry liners reduces mal-ovality and together with precision fitting of the liners has virtually eliminated liner cracking.
The use of BUT diesels for DMUs (diesel multiple units) dates from 1958, and included in the Swindon records is one of a unit that covered over 700,000 miles before it was transferred to another region. That was two or three years ago and it should by now be approaching the millionmile mark. In all probability the only original component is the crankcase but its record demonstrates the kind of longevity that can be achieved by advanced reconditioning methods. The BUT engines comprise the AEC A220 that develops 150 bhp at 1,800 rpm, the Leyland RE 680/1 having a comparable output at the same speed, the Albion 903 that develops 200 bhp, also at 1,800 rpm, and the Gardner 8L3 204 bhp diesel, the maximum speed of which is 1,200 While the cost of reconditioning a roadvehicle engine in a BR Engineering Works is strictly related to the high-grade workmanship involved (the profit motive is a "must" dictated by higher authority) it compares favourably with the cost of a typical factory reconditioned unit The BUT engines originally had a service life between major overhauls of 150,000 miles and extending the mileage to 220,000 is directly attributable to the advanced workshop practices employed. Routine maintenance of the engines, of the SCG R14 gearboxes and the auxiliary gear is performed at BR depots including the replacement of cylinder heads at intervals of 60,000 miles.
All major repair and overhaul work is undertaken in the workshops including crankshaft grinding and crank testing, the only job that is done by the engine manufacturer (if required) being crankshaft nitriding.
Road vehicle engines that are reconditioned join the BUT diesels on the flowline and after external cleaning, complete stripping and cleaning of the parts are processed in the same workshop sections. Components of the BUT engines are pooled, overhauled or replaced as necessary and re
assembled in a crankcase in matched combinations regardless of origin. If a batch of vehicle engines of the identical type were being reconditioned the same procedure would be followed.
Crankshafts are reground at the 220,000mile service, the AECs being reground twice (-Imm and imm) before replacement. Leyland and Albion crankshafts are reground up to five times but are generally replaced after three regrinds, the shafts being returned to Leylands for re-nitriding after the second regrind, and, if not replaced, after the fourth regrind. Relatively few Gardner engines are serviced in the Works, the same crankshaft regrinding procedures being normally applied to them.
Although on average the liners are worn less than 0.002in. after 220,000 miles they are renewed with the pistons at every service and whenever an engine is overhauled because of a failure. Piston/liner faults are the most common and of special interest failures normally occur in the first 60,000 miles. Failures are rare in the 60,000/220,000 mileage range of operations.
After external cleaning by the steam/ sodium metasilicate process, complete stripping and internal cleaning in a Dawson (Ardux bath) washing plant, all potentially re-usable components are given an "initial examination" in which every part is checked for wear against the maker's specification. Parts that can be re-used are then dispatched to the appropriate component section for overhaul or to await re-assembly.
Testing on a dynamometer occupies a total of 5hr. which includes an hour of full-power operation. The units are adequately run-in for normal working.
Used in multiples in a train set, the power units and gearboxes -have a unitized control system. On average the power available gives a power/unladen weight ratio of 200 bhp per 35 tons to which the weight of 60 seated passengers and a large number of standing passengers is added at peak periods. While the inter-city trains run for long periods without stopping, trains on the suburban lines have frequent stops and starts and the service conditions are probably more severe than the operating conditions of a typical trunkinE lorry or long-distance coach.
Looking ahead, the Swindon technicians forecast that increasing sophistication in the type of road vehicles employed in this country and in the organization of vehicle operations will enhance the usefulness of the sophisticated workshop that can tackle any kind of job with a high technical content as well as routine maintenance. And they are confident that BR Engineering will play an important part in this sophisticated scene.