Control and command circuits
HMS31-KY and VG31 reverse-bayonet connectors link rail vehicle control and command circuits. HMS31-KY uses crimp contacts; HMS31-K uses solder contacts.
Connectors for Rail Vehicles and Transit Equipment
Rolling stock connectors see continuous vibration, shock, water spray, oil and wide temperature swings, and must meet fire and smoke requirements.
For control, command and auxiliary circuits we offer HMS31-KY (NF F 61-030) and VG31 (VG 95234) reverse-bayonet connectors; for signal and data, 38999-type connectors including IP67 J599FS and cadmium-free marine-grade J599WR.
At a glance
- 150 A
VG31 reverse-bayonet contacts, from 13 A to 150 A
- IP67
HMS31-KY and VG31; J599FS with J1784FS backshells
- 400 g
J599HR plug shock rating, 3 ms
- 90
HMS31-KY insert arrangements, shell sizes 10SL to 40
Where they are used
Auxiliary power on rolling stock
HMS31-KY serves auxiliary power on locomotives and coaches, and VG31 serves traction auxiliary circuits, with contacts up to 150 A.
Exposed and high-vibration equipment
J599FS serves outdoor rail and transit equipment, J599WR rolling stock and wayside equipment, and J599HR bogies and traction equipment.
What the connectors must handle
Water and dirt
HMS31-KY and VG31 are sealed to IP67. J599FS reaches IP67 when mated with J1784FS waterproof backshells, which seal each wire with a double pressure plate.
Power and control contacts
HMS31-KY contacts carry 13–46 A; VG31 and HMS31-K carry 13–150 A within one connector family.
Fire behavior
HMS31-KY meets NF F 16-102 fire requirements; VG31 and HMS31-K use UL94 V-0 insulation.
Vibration and shock
HMS31-KY is rated for sine vibration at 5–150 Hz and 60 m/s². J599HR plugs take 400 g shock for 3 ms and hold with a double-locking coupling nut on J599 Series III receptacles.
Temperature and finish
HMS31-KY and VG31 operate from −55 to +125 °C. J599WR runs from −65 to +175 °C with a cadmium-free nickel-PTFE finish rated 240 h acid salt spray.
Harness routing
HMS31-KY offers 90 insert arrangements and straight or 90° backshells for cable clamps, conduit, sealed and shielded terminations.
Compare the series
Rail circular connectors
Swipe left or right to see all columns.
| Series | Coupling | Standard or type | Sealing | Current or contact sizes | Temperature | Datasheet |
|---|---|---|---|---|---|---|
| HMS31-KY | Reverse bayonet | NF F 61-030 | IP67 | 13–46 A | −55 to +125 °C | PDF, 264 KB |
| VG31 | Reverse bayonet | VG 95234 | IP67 | 13–150 A | −55 to +125 °C | PDF, 234 KB |
| HMS31-K | Reverse bayonet | MIL-DTL-5015 type | IP65 | 13–150 A | −55 to +125 °C | PDF, 218 KB |
| J599FS | Triple-start thread | GJB 599B (Series III type) | IP67 mated, with J1784FS backshells | 22D to 12 (5–23 A) | −65 to +200 °C (+175 °C cadmium) | PDF, 288 KB |
| J599WR | Triple-start thread | GJB 599B-2012 | Reinforced interfacial seal | 22D to 10 (5–33 A) | −65 to +175 °C | PDF, 290 KB |
How to choose
List the circuits
Give the current, wire gauge and insulation diameter for each control, signal and power circuit. This sets the contact size and grommet.
Choose the standard
HMS31-KY follows NF F 61-030 and VG31 follows VG 95234. If the harness mates with installed equipment, send its part number.
Set the environment
Give temperature, vibration, shock, water exposure and fire requirements. For underframe equipment, J599FS with J1784FS backshells reaches IP67.
Pick the insert arrangement
Choose the insert arrangement for the circuit count and working voltage.
Define mounting and cable exit
Send the panel drawing, cable routing, shielding and pin-out, and we will review your project.
Recommended series
HMS31-KY Reverse-Bayonet Crimp Connectors for Rail Vehicles, IP67
Rail vehicles · NF F 61-030 · IP67 · crimp contacts
VG31 Reverse-Bayonet Connectors, VG 95234 Type, IP67
VG 95234 · reverse bayonet · IP67 · rail and maglev
HMS31-K Reverse-Bayonet Circular Connectors, Solder Contacts
Reverse bayonet · solder contacts · IP65 · UL94 V-0
J599 Series III Circular Connectors (38999 Series III Type)
38999 Series III type · shell sizes 9–25 · 184 insert arrangements
J599FS IP67 Waterproof 38999-Type Connectors with J1784FS Backshells
IP67 with J1784FS backshell · threaded 38999 type · rain-tested
J599WR Marine-Grade 38999-Type Circular Connectors, Cadmium-Free
Cadmium-free nickel-PTFE finish · marine-grade · up to 5000 mating cycles
XY2 Lightweight Micro Circular Connectors
≈ 30 % lighter, 50 % smaller than Series III · threaded · 9 shell sizes
J599HR High-Vibration 38999 Series III-Type Plugs
400 g shock · 1.5 g²/Hz random vibration · 1000 mating cycles
All series can be customized — contact counts, cable lengths, materials and finishes.
Related guides
MIL-DTL-5015 Type Connectors for Rail Vehicles
Why MIL-DTL-5015 type connectors are used on rolling stock: threaded vs reverse-bayonet coupling, service ratings and rail standards.
IP67, IP68 and Hermetic Sealing: What Connector Ratings Mean
What IP67 and IP68 mean for connectors, how they differ from hermetic sealing and underwater depth ratings, and what to put in your specification.
Withstanding Voltage vs Working Voltage in Connectors
Why a connector's withstanding (test) voltage is not its working voltage, how altitude changes it, and how to choose a safe working voltage.
Choosing Connector Contact Size by Current and Wire Gauge
How to pick 38999-type contact sizes 22D, 20, 16, 12 and 10 by current and wire gauge, with a reference table and notes on derating and mixed layouts.
FAQ
Which connectors follow rail standards?
HMS31-KY is built to NF F 61-030 with MIL-DTL-5015-type insert arrangements and meets NF F 16-102 fire requirements. VG31 is built to VG 95234.
How do I get IP67 on a 38999-type connector?
Use J599FS with J1784FS waterproof backshells. The mated connector is rated IP67, and the backshell seals each wire with a double pressure plate.
Which rail connectors carry the highest current?
VG31 and HMS31-K carry 13–150 A; HMS31-KY carries 13–46 A.
Which connector suits bogies and high vibration?
J599HR plugs are rated 400 g shock for 3 ms and use a composite double-locking anti-decoupling coupling nut. They mate with J599 Series III receptacles.
What should I send for a rail harness inquiry?
Send the part number or required standard, pin-out, current and working voltage, environment, mounting and cable routing, plus a drawing if you have one. We confirm receipt within 1 business day.
From sample to production
Send your requirements
Part number, drawing, pin-out or a short description of your application.
Configuration and quote
Our engineers match the configuration and reply with a drawing and quotation.
Samples
Samples are built to order. The minimum order quantity is 10 pieces, and samples and production orders each take 4–8 weeks. Third-party testing to your specification is available on request.
Your approval
You test the samples in your own equipment and approve them.
Series production
Production follows the approved sample configuration, with machining, molding, plating and assembly in our own Shenyang factory.
Need a quote or a drawing?
Send your part number, pin-out or drawing. Every inquiry is acknowledged by email within 1 business day, and an engineer follows up with a matched configuration, drawing or quotation.