A brief glance of a WAP 4 Locomotive and my experience.

 WAP-4 is a common electric locomotive used in India. It is capable of hauling 26 coaches at a speed of 140 km/h.

The locomotive was developed, after a previous class WAP-1 was found inadequate to haul the longer, heavier express trains (24 - 26 coaches) that were becoming the mainstay of the Indian Railways network. It was introduced in 1994, with a similar body shell to the WAP-1 class, but with Hitachi traction motors developing 5000 hp (5350 hp starting).

Electricals are traditional DC loco type tap changers, driving 6 traction motors arranged in Co-Co fashion. This locomotive has proved to be highly successful, with over 800 units in service and more being produced. Newer examples have been fitted with Microprocessor Controlled diagnostics, Static Converter units (instead of arnos) and roof mounted Dynamic (Rheostatic) Brakes.

The loco has a streamlined twin cab carbody design, with top-mounted headlamps. The first 150 or so units had the headlamp mounted at waist level, with the lights being mounted in a protruding nacelle. Later on the headlamps were placed in a recessed nacelle, and from road # 22579 onward, the headlamps were moved to the top.

Newer locos also feature larger windshields, more spacious driver cabin with bucket type seats and ergonomic controls. The control panel also features a mix of digital and analog displays in newer units (all analog display in older versions).

The loco features higher power rated silicon rectifiers and indigenously-designed 5400kVA transformer coupled with Hitachi HS15250 traction motors. Starting power is 5,350 hp (3,990 kW), with 5,000 hp (3,700 kW) being supplied continuously.

Original units were weighed 120 tonnes, which was brought down to 112 tonnes through the usage of lighter material.

WAP-1,WAP-3 and WAP-6 units were rebuilt to WAP-4 specifications after replacing the bogies & electricals.

The class is used to haul the premier Rajdhani & Shatabdi expresses at 140 km/h. In trials, the locomotive has achieved a top speed of 169 km/h, though Indian Railways limits its top speed to 140 km/h.

With a 24 coach passenger train, the acceleration time / distances are:

110 km/h - 338 seconds (6.8 km)

120 km/h - 455 seconds (10.5 km)

130 km/h - 741 seconds (20.5 km)

Starting Tractive Effort (Te) - 32000 kg/force

A short footplating video of a WAP 4. (P4 Footplate)

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