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 
MAKERS
Page 44
Page 45
If you've noticed an error in this article please click here to report it so we can fix it.
Careful specification of bodywork can pay dividends in enhanced productivity. On rigids it can be as simple as selecting lightweight panels and adding a tail-lift or side-access door. The possibilities for trailers are more numerous, and include demountable bodies and buckleless curtainsiders. Following the weights uplift tc 44 tonnes, however, one productivity-boosting configuration is taking the trailer building industry by storm: double-deckers.
ouble decks were once confined to high-volume/lowweight sectors such as parcels trunking. At 44 tonnes gross they are attractive to general haulage operations because, despite the extra weight of the equipment, the payload is still a useful 2425 tonnes.
It's not hard to see the attraction. By doubling the available load space per trip, operators can reduce fleet size, saving not just on fuel and service costs but on drivers' wages as well. There is no height restriction for domestic operations, and double decks can be as high as 4.9m. In practice a typical height is 4.4m—tall enough to provide enough interior space and to avoid loading problems, but not so tall that the centre of gravity becomes dangerously high or bridge heights become too much of an issue when picking routes.
Retailers have seized on double decks as a means of cutting the costs of distribution. John Lewis Partnership has been using Don-Bur lifting decks for the past two years; Halfords has switched to Montracon double-deckers for deliveries to its out-of-town superstores, Bakers are also enthusiastic users—Cartwright supplies several bakeries, including 'Vied Bakeries; and Gray & Adams has been building twin-deck trailers for supermarket distribution operations for several years, and is now winning orders for dryfreight trailers. Double decks work equally well wit straight, step-frame and mega-trailer second decks can be fixed, lifting, pivo ing, variable height and even removabli Internal tail-lifts with three-quarte length fixed decks are also popular ft their loading flexibility. Load units ofte dictate the specification. Roll cages, ft example, are usually taller than pallet so they require the extra internal heigl of a step-frame trailer; curtain-side double-deckers give more loading flexib ity for return loads. Don-Bur's ratchet-deck curtainsider designed for operations where load ifigurations can change. It has up to ee separate platforms located in vertipillars on each side. The decks are sed and lowered by fork-lift when aden. Swinging latches in each corner in slots at 300mm intervals in the pils while they are being lifted. When they being lowered, the latches swing tipletely free of the pillars to speed up operation.
Although they can be removed corntely, the decks usually rest on the main a when not in use. Each of these decks 3 a capacity of 4,000kg and measures lx400x500mm.
Ken Wilson, managing director of adford-based Wilson trailers, says the :re payload possible at 44 tonnes ikes a pivoting deck more attractive to ieral hauliers. "They are not so word about loss of payload on the return )," he says. Pivoting decks turn through Y° when not in use and are usually 3ured along the centre spine, forming a id central partition. Wilson has just
developed what it calls a "butterfly" design that leaves clear cross-access for loading.
Cartwright sales manager Mark Jones warns that operators loading double-deck long
wheelbase stepframe trailers should ensure that there is enough weight going through the kingpin: "The second deck does not extend into the neck section, so there is a risk of overloading the trailer bogie."
Nick Liston, Montracon's engineering manager, reports that operators are becoming more specific about power arrangements on trailers: "Power supply has traditionally been through the tractive units, but operators are now looking at stand-alone systems, including plug-in trailer units and auxiliary power for taillifts," he says.
Montracon's portfolio has grown with the acquisition of Northern Ireland-based Wilson Double-Deck Trailers—the company which pioneered ultra-low-floor double-deck trailers with independent suspension.
Lifting-deck designs offer excellent loading flexibility, but at £15,000 or more they are mainly the preserve of dedicated distribution operations.
Lifting decks have capacities of between eight and 10 tonnes, and are powered hydraulically. Cartwright's design has hydraulic rams in each corner, with sensors to ensure the deck remains level. Don-Bur and Montracon prefer an under-deck ram, with cables in each corner to do the actual lifting.
Don-Bur engineering director Andy Richardson, says deck operation and diagnostics have greatly improved: "We changed to proximity switches to get more responsive deck-position sensing capability. Relays have been replaced with electronic connections, which have helped installation and improved diagnostic capability, if there is a problem such as a valve going, the Siemens diagnostic unit tells the user exactly what it is. There's no code to decipher."
Cartwright's Transdeck is not so much a double-decker, more a loading aid. The hydraulic platform moves inside the trailer, allowing goods to be loaded right up to the roof with or without a secondary decking system.
It's slower than some methods of loading, but is favoured by, for example, furniture carriers and garment retailers, because the height of the second deck can be tailored precisely for each load unit using horizontal load bars attached to anchor points in the side walls. Dawes Fashion has almost doubled the number of garments it carries from 5,000 to 9,000 a trip using its first Transdeck system, saving one trunking run each night. III by Sharon Clancy