Blaw Knox K5735
Contents
Overview
Little is known about Blaw Knox K5735. It was said to be a “Blaw Knox variant of the PL7”, a claim made under the misunderstanding that the PL numbers represented tower types rather than contracts. The specific region to which this PL7 contract belongs is not known, nor where these towers may exist. K5735 was misreported to be the design used for the Lydney towers but those turned out to be an unidentified design closer to CE PL4, itself a Blaw Knox design.
The DD2 type is virtually identical to SWE PL16 D2. Aside from draughting discrepancies, the only change appears to be the modification to accommodate double earthwires, specifically the addition of an earthwire crossarm along with a height increase of the top phase crossarm to match the change in tower height. Likewise, the DD30 tower is virtually identical to PL16 D30.
In keeping with tradition, the DD60 and DD90 towers share the same design as DD30 and are simply wider at the base. This practice was not continued with PL16, whose D60/DD60 and D90/DD90 towers each had its own design of tower body.
The CE PL3 and CE PL4 drawings recovered to date are from 1936. The K5735 DD30 drawing (XM1742-29) dates to 1940 (DD2, DD60 and DD90 are from 1941), while the oldest PL16 drawings recovered date to 1944. This puts K5735 presently as an older design than SWE PL16.
General data
Design contractor | Blaw Knox, Milliken Brothers branch |
---|---|
Found | ❌ |
Height (straight line tower) | 89′–9″ (27.4 m) (DD2) |
Voltage | 132 kV |
Dates back to | 1940 (drawings) |
Known conductors | Single |
Tower forms
The DD90 drawing references the D90 (“Arrangement of crossarms are similar to crossarms for tower type D90° See drg. no. XM1742-26A”); the series quite likely included a full set of single earthwire types. The only drawings originally provided by National Grid to another individual were DD2, DD30, DD60 and DD90 and the rest were either withheld or were not in National Grid’s posession. National Grid should have a drawing register for the type, however.
The following diagrams are shown to scale at 12 pixels per metre:
The dashed line within the peak of each angle tower represents a member that is only present on earthwire changeover towers.
Tower details
Crossarm width is the total width across the widest crossarm. Phase clearances are given top-to-bottom (EW to top phase, top to middle, middle to bottom) and are the vertical separations between crossarms only.
Type | Source | Height | Base width | Crossarm width | Phase clearances |
---|---|---|---|---|---|
K5735 DD2 | XM1742-27 | 89′–9″ (27.4 m) | 13′–9″ (4.2 m) | 30′–6″ (9.3 m) | 4′–9″, 13′–6″, 12′ |
K5735 DD30 | XM1742-29 | 87′–9″ (26.7 m) | ca. 20′–0″ (6.1 m) | 30′–6″ (9.3 m) | 11′, 12′, 12′ |
K5735 DD60 | XM1742-30 | 87′–9″ (26.7 m) | 21′–6″ (6.6 m) | 32′–6″ (9.9 m) | 11′, 12′, 12′ |
K5735 D90 | XM1742-26A | Not recovered | |||
K5735 DD90 | XM1742-31 | 87′–9″ (26.7 m) | 22′–6″ (6.9 m) | 38′–6″ (11.7 m) | 11′, 12′, 12′ |