Theodore2940 at 09:52, 7 January 2026

2026-01-07T09:52:30Z

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{{Short description|Indian Railways class diesel–electric locomotive}}
{{More citations needed|date=November 2024}}
{{Infobox locomotive
| name = YDM-4
| powertype = Diesel
| image = YDM4-6669 Jaipur Junction, 2008 (1).JPG
| alt =
| caption = Phulera based YDM-4 at Jaipur Jn.
| builder = [[American Locomotive Company|Alco]], [[Montreal Locomotive Works|MLW]], [[Banaras Locomotive Works|BLW]]
| ordernumber =
| serialnumber =
| buildmodel = [[ALCO DL535|DL535]], [[ALCO DL535A|DL535A]], [[RSD-30]], [[D13E]].
| builddate = 1961–1993
| totalproduction = YDM-4: 695
| rebuilder =
| rebuilddate =
| numberrebuilt =
| aarwheels =
| uicclass = [[Co-Co locomotives|Co-Co]]
| gauge = {{RailGauge|1000mm|allk=on}}
| trucks =
| bogies = ALCO Asymmetric cast frame trimount
| wheeldiameter = {{convert|965|mm|in|2|abbr=on}}
| trailingdiameter =
| minimumcurve =
| wheelbase =
| length = {{convert|15.60|m|ftin|abbr=on|frac=8}}
| width = {{convert|2730|mm|ftin|frac=8|abbr=on}}
| height = {{convert|3635|mm|ftin|frac=8|abbr=on}}
| axleload = {{convert|12000|kg|abbr=on}}
| weightondrivers =
| locoweight = {{convert|72000|kg|abbr=on}} ALCo/DLW, {{convert|67000|kg|abbr=on}} MLW
| fueltype = [[Biodiesel|Diesel]]
| fuelcap = {{convert|3000|L|abbr=on}}
| lubecap = {{convert|530|L|abbr=on}}, {{convert|630|L|abbr=on}} DLW
| coolantcap =
| watercap = {{convert|22|L|abbr=on}}, {{convert|28|L|abbr=on}} DLW
| sandcap =
| consumption =
| watercons =
| primemover = [[ALCO 251|ALCO 251-D]]
| rpmrange = 400-1100
| enginetype = [[Straight-six engine|Inline-6]] [[Diesel engine|diesel]]
| aspiration = [[Turbo-supercharger|Turbo-supercharged]]
| displacement = '''''(?)'''''
| alternator =
| generator = [[Direct current|DC]]
| tractionmotors = 6 DC
| cylindercount = 6
| cylindersize = {{convert|228 x 267|mm|in|2|abbr=on}} [[Bore (engine)|bore]] x [[Stroke (engine)|stroke]]
| transmission = [[Diesel–electric transmission]]
| multipleworking = 2
| maxspeed = {{convert|96|km/h|0|abbr=on}}
| poweroutput = Max: {{convert|1400|HP|abbr=on}}<br>Site rated: {{convert|1300|HP|abbr=on}}
| tractiveeffort = {{convert|18.935|t|0|abbr=on}} maximum {{convert|16.050|t|0|abbr=on}} continuous
| factorofadhesion =
| trainheating =
| locobrakes = 28LV-1, [[Railway air brake|Air brake]] for Locomotive using SA-9 brake handle
| locobrakeforce =
| trainbrakes = Originally [[Vacuum brake|Vacuum]] using A-9 brake handle, some modified to [[Vacuum brake#Dual brakes|Dual]]
| safety =
| operator = [[Indian Railways]], [[IRCON]], [[Keretapi Tanah Melayu|KTMB Malaysia]], [[Rail transport in Myanmar|Myanmar Railways]], [[Vietnam Railways]], [[Rail transport in Cambodia|Cambodian Railways]], [[Mozambique Ports and Railways]], [[Togorail]]
| operatorclass =
| powerclass =
| numinclass =
| fleetnumbers = 6020-6049 ALCo, 6105-6129 ALCo, 6130-6198 MLW, 6199-6258 DLW, 6259-6288 MLW, 6289-6769 DLW
| officialname =
| nicknames =
| axleloadclass =
| locale = All over Indian Railways<br>Leased to various operators (KTMB Malaysia, Myanmar Railway, Cambodian Railways) <br>25 units operated by Vietnam Railways
| deliverydate =
| firstrundate =
| lastrundate =
| retiredate =
| withdrawndate =
| preservedunits = 3
| restoredate =
| scrapdate =
| currentowner = Indian Railway, IRCON, KTMB Malaysia, Myanmar Railway, Vietnam Railways, Cambodian Railways
| disposition = active
}}

The '''YDM-4''' is a class of [[diesel locomotive]]s operating on [[Indian Railways]]. The first units were built by the [[American Locomotive Company]] (Alco) in 1961. Since 1968, members of the class have been manufactured in India by the [[Banaras Locomotive Works]] (BLW), Varanasi. The model name stands for [[metre gauge]] (Y), diesel (D), mixed traffic (M) engine. The YDM-4 has been the most successful metre gauge diesel locomotive in India. The YDM-4 locos have a maximum speed of {{convert|100|km/h|abbr=on}},<ref name = "IRFCA">{{cite web |url = http://www.irfca.org/faq/faq-loco-diesel-mg.html |title = YDM–4, YDM–4A |publisher = Indian Railways Fan Club|access-date = March 29, 2016}}</ref> restricted to {{convert|85|km/h|abbr=on}}.<ref name = "RDSO">{{cite web |url = http://www.rdso.indianrailways.gov.in/works/uploads/File/19_08_67.pdf |title = YDM4 Loco Max Operating Speed 85 kmph |author= RDSO |date= 19 August 1967 |publisher = Research Designs and Standards Organisation (RDSO) |access-date = March 29, 2016}}</ref>

The '''YDM-4A''' is a variant of the YDM-4 that is supplied by [[Montreal Locomotive Works|MLW]]. Originally equipped with [[vacuum brake]]s, some were later equipped with dual brakes, particularly those working in the [[Northeast Frontier Railway]].

==History==
In the mid 1950s [[Indian Railways]] began introducing diesel locomotives to its metre gauge system. Metre gauge, though rare in the 21st century, used to be a dominant gauge at that time. After the introduction of YDM-1 locomotives by the [[North British Locomotive Company]], Indian Railway considered more powerful ones and hence [[Electro-Motive Diesel|General Motors Electro-Motive Division]] (EMD) and the [[American Locomotive Company]] (ALCO) submitted designs of [[Indian locomotive class YDM-3|YDM-3]]/[[Indian locomotive class YDM-5|YDM-5]] ([[EMD 567|12-567C]]) and YDM-4 respectively for new diesel locomotives. Each company supplied 30 locomotives in 1961. While the YDM-3 was 13 tons lighter than the YDM-4, Indian Railways opted for the ALCO design because of the heavier axle load and technology agreement that would allow these locomotives to be manufactured in India.

After [[Banaras Locomotive Works]] (BLW) completed construction of its factory in Varanasi, production of the class began in India. The initial 30 YDM-4 locomotives supplied by ALCO in 1961 were numbered between #6020 and #6049. Another batch of 8 locomotives soon followed and were numbered #6105 to #6112. YDM-4 #6113-6129 were built around 1964. Siliguri Diesel Locoshed was the first DLS to station YDM-4 locomotives in 1962. The very first YDM4, #6020, was allotted to the New Guwahati Diesel Loco Shed, which was an outbase of Siliguri DLS on 30 October 1962.

YDM4 #6130 to #6198 were built by [[Montreal Locomotive Works]] (MLW) in 1964 under the license of ALCO and were classified as YDM-4A. All the YDM-4 delivered up to then were presumably based at three premier DLS across India namely Siliguri (SGUJ), Ponmalai Goldenrock (GOC) and Sabarmati (SBI). Another batch of YDM-4A was dispatched from MLW in 1969, numbered #6259 to #6288.

The first YDM-4 built by Banaras Locomotive Works (BLW) Varanasi was #6199 ''Hubli''. This loco entered service in 1968 and was dedicated to the then Deputy Prime Minister of India, [[Morarji Desai]]. DLW built locos in the range #6199 to #6258.

From 1969 till 1993 DLW produced YDM-4 locomotives for Indian Railways in the number range #6289 to #6769. The last YDM-4 was based at Rangapara North outbase of Siliguri DLS but later on transferred to [[Myanmar Railways|Myanmar (Burma) Railways]] and possibly renumbered as DF1332.<ref>{{cite web |url = https://www.facebook.com/YDM4-492488834113077/info?tab=page_info|title=YDM4 - About|website=[[Facebook]] }}</ref>{{Better source needed|date=October 2018}}

==Locomotive sheds==
{| class="wikitable"
|-
! Zone !! Name !! Shed Code !! Quantity
|-
| [[North Eastern Railway zone|North Eastern Railway]] || [[Izzatnagar railway station|Izzatnagar]] || IZN|| 10
|-
| [[North Western Railway zone|North Western Railway]] || [[Mavli Junction railway station|Mavli]] || MVJ || 8
|-
| [[Southern Railway zone|Southern Railway]] || [[Diesel Loco Shed, Golden Rock|Ponmalai Goldenrock]] || GOC|| 5
|-
| rowspan="2" |[[Western Railway zone|Western Railway]] || [[Diesel Loco Shed, Sabarmati|Sabarmati]] || SBI || 15
|-
| [[Diesel Loco Shed, Mhow|Mhow]] || MHOW || 5
|-
| colspan="3" | '''Total Locomotives active as June 2025'''<ref>{{Cite web|title=Railway Website Mechanical Department|url=http://www.indianrailways.gov.in/railwayboard/view_section.jsp?lang=0&id=0,1,304,366,541,710,717|access-date=1 December 2021}}</ref> || 43
|-
|}


==Technical specifications==

Source:<ref>{{cite web|url=http://www.irfca.org/faq/faq-loco2d.html#wdm-2|title=[IRFCA] Indian Railways FAQ: Locomotives -- Specific classes : AC Electric|website=www.irfca.org}}</ref>{{Irrelevant citation|date=November 2024}}

{| class="wikitable"
|Manufacturers
|Alco, MLW, DLW
|-
|Engine
|Alco 251-D, [[Straight-six engine|Inline-6]], {{convert|1,400|hp|abbr=on|lk=on}} ({{convert|1,300|hp|abbr=on|disp=or}} site rating) with Alco turbocharged engine. 1,100 rpm max, 400 rpm idle; {{convert|228|x|267|mm|in|2|abbr=on}} bore x stroke; compression ratio 12.5:1.
|-
|Transmission
|Electric, DC-DC (DC Generator and DC Traction motor)
|-
|[[Traction motor]]s
|GE for original Alco and MLW models, BHEL for DLW
|-
|[[Axle load]]
|{{convert|12.0|t|abbr=on}}
|-
|total weight
|{{convert|72.0|t|abbr=on}} ALCo and DLW, {{convert|67.0|t|abbr=on}} MLW
|-
|[[Bogie]]s
|Alco design cast frame trimount ([[Co-Co engine|Co-Co]]) bogies with asymmetrical arrangement of traction motors
|-
|Starting TE
|{{convert|18.94|t|abbr=on}}
|-
|Continuous TE
|{{convert|16.05|t|abbr=on}}
|-
|}

==References==
{{Reflist}}

==External links==
* [http://www.irfca.org/docs/ydm4-internals.html YDM-4 Diesel Locomotive Internals]

{{Metre gauge locomotives of India|state=expanded}}

[[Category:Diesel–electric locomotives of India|M, Y-4]]
[[Category:Co-Co locomotives]]
[[Category:ALCO locomotives]]
[[Category:Banaras Locomotive Works locomotives]]
[[Category:MLW locomotives]]
[[Category:Railway locomotives introduced in 1961]]
[[Category:Metre-gauge locomotives]]

Indian locomotive class YDM-4 - Revision history

Theodore2940 at 09:52, 7 January 2026