Project record · Overseas · Locomotive overhaul and mine railway

Cast Copper DLO Cable Lugs, 1100/24, for Locomotive Traction Motor Leads

An overseas buyer serving locomotive overhaul workshops and mine railways sent us a worn cable lug with one line still legible on the tongue: 1100/24. They needed new DLO cable lugs to the same pattern, for traction motor leads and main generator connections, together with the 444.4 kcmil diesel locomotive cable the lugs go on. TEBAOFLEX cast the lug bodies in copper, bored the crimp barrels, check-weighed the batch, tin-plated the parts and laser-marked each one 1100/24. The cable was our standard 2 kV DLO. Cable and lugs shipped as separate items for crimping in the workshop.

Project record

Why DLO cable needs its own lug

DLO cable is built to be bent into a locomotive carbody and to live with vibration. To get that flexibility, the conductor is rope-lay Class I tinned copper made of 24 AWG strands, more than a thousand of them in the larger sizes. That has two consequences at the termination:

• The conductor is bigger than the kcmil figure suggests. A finely stranded conductor has more air between the strands than a Class B building-wire conductor of the same cross-section. Our 444.4 kcmil DLO conductor measures 20.0 mm across. A lug barrel sized for building wire of the same kcmil will not accept it.
• Strands must not be trimmed to fit. Cutting away outer strands to push the conductor into a small barrel removes copper from the circuit and leaves a hot joint.
• The joint works hard. Traction motor leads and main generator connections carry high current under constant vibration, and they are unbolted and re-made at overhaul. That is why this lug family is cast, with a thick one-piece tongue and a heavy barrel wall, instead of being formed from tube.

So DLO lugs are sized by the strand designation of the conductor, not by AWG or kcmil alone, and the designation is marked on the lug.

Reading the stamp: what 1100/24 means

The mark on the buyer’s old lug and on the new ones is a conductor designation: about 1,100 strands of 24 AWG wire. One 24 AWG strand is 404 circular mils, and 1,100 × 404 = 444,400 circular mils. A lug marked 1100/24 is a lug for 444.4 kcmil DLO cable.

The designation names the conductor class, not an exact count. Rope-lay conductors are built from bunched groups, so the real number of strands depends on the group arrangement each cable maker uses. Our own construction table lists the 444.4 kcmil conductor as 1110/24; other published DLO tables show counts between 1,100 and about 1,120 for the same size. All of them terminate in a 1100/24 lug.

From the buyer’s sample to a finished lug

Lugs for DLO cable are a small-batch product. We made this batch to the buyer’s sample and photographed each stage.

1. Casting

The lug bodies are cast in copper as one piece: barrel, transition and tongue. At this stage the barrel is still solid.

2. Boring the barrel and drilling the stud hole

Each casting is held in a lathe fixture and the crimp barrel is bored from solid. Boring after casting gives a clean, round, concentric bore, which matters for an even crimp. The stud hole in the tongue is drilled to the 1/2 in stud size the buyer specified.

3. Check-weighing

After machining, the lugs are weighed as a batch. Nine lugs came to 4.435 kg, about 0.49 kg each. A casting with internal porosity or an off-size barrel wall shows up as a weight difference before it shows up anywhere else, so this is a fast check on the copper section that will carry the current.

4. Tin plating and laser marking

The machined lugs are tin-plated all over for corrosion resistance and to match the tinned strands of the DLO conductor. The size code is then laser-marked on the tongue, so the workshop can match lug to cable at a glance, and can still read the size at the next overhaul.

Lug data for this order

The buyer works to a North American reference catalog, so the lug follows that published pattern. Dimensions are the catalog’s approximate dimensions in inches; millimetres are our conversion.

Cast copper DLO lug sizes and reference catalog numbers

TEBAOFLEX supplies cast copper lugs as a regular item alongside DLO cable, made to the buyer’s sample or drawing. The three tables below list the common patterns for diesel locomotive cable with the catalog numbers buyers usually quote. Dimensions are approximate, in inches (1 in = 25.4 mm). Add the stud size you need if it is not listed; blank tongues are also available.

One-hole tongue, side-formed

The pattern made for this order. The side-formed tongue is flush with one side of the barrel, so the conductor sits offset from the mounting surface.

Two-hole tongue, side-formed

Two-hole tongue, center-formed

The center-formed tongue sits on the barrel centre line and keeps the conductor aligned with the mounting surface.

Also made to order: blank-tongue lugs for field drilling, 90° cast copper elbows for 775/24 and 550/24 conductors, and cast copper reducers for 1100/24, 775/24 and 550/24.

Reference note: catalog numbers and dimensions are those published by Penn-Union for its locomotive cast copper lugs, and the die index numbers refer to Thomas & Betts (T&B) compression tooling. They are shown so buyers can identify the pattern they need. Penn-Union and T&B are trademarks of their respective owners. TEBAOFLEX manufactures to the buyer’s sample or drawing and is not affiliated with either company.

The cable side: 444.4 kcmil DLO, 2 kV

The lugs went out with our standard 2 kV DLO cable: rope-lay Class I tinned copper conductor, EPR insulation rated 90 °C wet or dry, and a black thermoset CPE jacket. The size that takes a 1100/24 lug is below; the full range runs from 14 AWG to 1111.1 kcmil.

For current ratings, see the DLO cable ampacity chart, which covers free air, raceway and derating.

Notes for crimping DLO lugs

These are general workshop points, not a substitute for the tool maker’s instructions:

• Match the lug mark to the cable: 1100/24 lug on 444.4 kcmil DLO. Do not go by kcmil from a building-wire chart.
• Strip to the barrel depth and keep every strand. If the conductor will not enter the barrel, the lug is the wrong size.
• Use a hydraulic compression tool with the die called for in the table. The catalog lists these lugs for 12-ton, 20-ton and 40-ton compression heads.
• Seal the barrel end with heat-shrink where the joint sees oil, water or brake dust.
• Torque the stud connection to the equipment maker’s figure, not by feel.

What to send us for DLO cable and lugs

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