Off-Highway Powertrain Services
What Are Off-Highway Powertrain Services?
Off-highway powertrain services are the specialized inspection, rebuild, testing, and parts support operations that keep heavy equipment drivetrain systems running in construction, mining, agriculture, and industrial environments. HMS has delivered these services from its Westville, New Jersey facility since 1973 — supporting transmissions, torque converters, axle systems, turbine starting systems, and OEM drivetrain components across North America and internationally.
Heavy equipment does not fail on a schedule. When a transmission goes down on a job site or a turbine starter fails at a power plant, every hour of downtime carries a real cost. Consequently, off-highway powertrain services done correctly are not just about fixing what broke — they are about restoring performance, preventing the next failure, and getting critical equipment back to work. HMS brings more than 100 man-years of engineering experience to every engagement. Furthermore, our team includes registered professional engineers, manufacturer-trained technicians, and a Service Manager with over 30 years of hands-on drivetrain experience. Additionally, we hold ISO 9001:2015 certification and serve as an authorized service center for Allison Off-Highway transmissions. When your equipment goes down, HMS has the credentials and capability to bring it back.
What HMS Off-Highway Powertrain Services Cover
- Transmission inspection, rebuild, and testing — authorized Allison Off-Highway service center with ISO 9001:2015 certification
- Torque converter teardown, component replacement, industrial cleaning, reassembly, and functional testing
- Axle service and repair including differential inspection, bearing replacement, gear setup, and full assembly rebuild
- OEM parts distribution for Allison Spicer powertrain components — visit our parts inventory for availability
- Turbine starting system design, manufacture, and testing for applications from 1/2 MW to 150 megawatts
- Custom OEM drivetrain engineering and manufacturing with registered professional engineers on staff
- Full field support from inception through installation, testing, training, and ongoing field service
Why Do Off-Highway Transmissions Require a Specialist?
Off-highway transmissions operate under load conditions that standard repair shops are not equipped to diagnose, rebuild, or test. Consequently, a general repair facility without manufacturer authorization, dedicated test stands, and hands-on drivetrain experience produces rebuilds that fail again. HMS technicians have rebuilt these systems for over 50 years — and every unit is verified on our transmission and torque converter test stands before it leaves our facility.
What HMS Services Support Your Equipment
Every service HMS provides connects to keeping your equipment productive and your operation running. However, the specific combination of capabilities we bring to each engagement is what separates HMS from a general drivetrain shop.
Transmission and Torque Converter Rebuild. We perform complete disassembly, precision measurement, component replacement, and operational testing for off-highway transmissions and torque converters. Moreover, as an authorized Allison Off-Highway service center, our technicians follow manufacturer-specified rebuild procedures using genuine OEM components — returning your equipment to factory performance levels. Need parts before or after a rebuild? Our parts inventory supports both repair work and direct customer orders.
Axle and Differential Service. Heavy-duty axle systems in mining, construction, and agricultural equipment operate under extreme stress. Consequently, our technicians perform differential inspection, bearing and seal replacement, gear setup and adjustment, and complete axle assembly rebuilds for demanding field conditions.
OEM Parts Distribution. HMS maintains inventory and sourcing capability for genuine Allison Spicer powertrain components. Furthermore, Bill Sasser — our Sales Manager with 27 years of drivetrain parts experience — provides technical identification support so you receive the correct part for your specific application the first time.
Custom OEM Drivetrain Engineering. Original equipment manufacturers requiring custom drivetrain solutions work with our registered professional engineering staff to design, develop, and manufacture systems for specific application requirements. Additionally, HMS supports prototype development, small-batch manufacturing, and reverse engineering for obsolete components no longer available through standard channels.
HMS Starting Systems — Where This Company Began
In 1973, founder Howard Rosenbloom — working alongside co-founders Milton Tottle and Nate Goodman — developed a turbine starter system for Westinghouse using rugged off-highway drivetrain components. That project became the foundation of Hydro-Mechanical Systems. More than 50 years and 100 man-years of engineering experience later, HMS Starting Systems remains a specialized capability that no standard drivetrain shop can replicate.
HMS has supplied many major turbine manufacturers and packagers with starting systems. Coupled with our testing expertise, our assemblies ship pre-tested and factory set for optimum performance. Furthermore, with in-house engineering expertise and the extended services of our vendor network, HMS can meet your most demanding application requirements.
We design, manufacture, test, and ship custom starting systems — hydraulic, electric, or diesel — for turbine applications ranging from 1/2 MW to 150 megawatts. Starters range from simple hydrostatic motors to complete enclosed assemblies including hydrostatic pumps with oil storage tanks to large electric or diesel engines coupled with industrial torque converters and associated drive trains. Additionally, HMS supports customers from inception through installation, testing, training, and ongoing field support.
Designed systems include:
- Hydrostatic motors and hydraulic pumps
- Electric motor and diesel engine prime movers
- Cooling systems and enclosed power units
- Closed or open loop hydraulic circuits
- High pressure filter systems and turning gear drives
- Synchronizing clutch drives and hazard area classified configurations
- Compliance to international specifications including IEC, RINA, and ABS
Technical support capabilities include:
- Multi-lingual support in Italian, French, and German
- Representation in Italy, Germany, the United Kingdom, and Japan
- AutoCAD documentation with email delivery of engineering drawings
- ISO 18/13 test equipment and hydraulic test bench to Code 62 capacity
- Electric motor rotating drive, packaged electrical controls, and PLC systems
- 50 or 60 Hz system configurations
- Registered professional engineering staff on site
Notable HMS Starting Systems applications:
In Key West, Florida, an HMS Power System provides both turning gear and starting acceleration for an orphaned retired generator — now operating as an active synchronous condenser balancing utility electrical demand. This project was created in cooperation with General Electric.
HMS also engineered a packaged power unit for Fiat that converts AC Electric Motor Power to variable hydraulic power using tandem pumps — providing both a hydraulic starter and hydraulic turning gear for GE LM Series Gas Turbines.
In the Mediterranean, several large ferries powered by GE gas turbines transport vehicles across open water with HMS providing the key hydraulic starting component.
How Does a Proper Drivetrain Rebuild Prevent Repeat Failures?
Repeat drivetrain failures happen when rebuilds address symptoms instead of root causes — and when components return to service without proper testing. Consequently, every HMS rebuild follows a documented inspection, precision measurement, and test stand verification process. Rocky Morgan, our Service Manager with 30+ years of drivetrain experience, oversees every rebuild from teardown through final testing — so failures do not come back.
HMS Starting Systems — Completed Project Track Record
Hydro-Mechanical Systems has teamed with major OEMs in the engineering, design, development, and production of the following successfully completed projects:
- 9 units — 2,500 HP Diesel/Torque Converter systems for the TG50 Gas Turbine
- 16 units — Hydrostatic Starting and Turning Systems for the GE LM6000 Gas Turbine
- 2 units — Hydrostatic Starting Systems for the GE LM2500+ Gas Turbine
- Fast Ferries Projects, 2 generations — Hydrostatic Starting, Turning, and Motoring Units for the GE LM2500 Marine Gas Turbine
- 1 unit — Frame 1001 Diesel/Torque Converter
- 6 units — W-301 Diesel/Torque Converter
- 100 units — W-501AA Electric Motor/Torque Converter/Turning
- 200+ units — W-501B Electric Motor/Torque Converter/Turning
- 200+ units — W-501C Electric Motor/Torque Converter/Turning
- 200+ units — W-501D1-D4 Electric Motor/Torque Converter/Turning
- 8 units — W-501D5 Electric Motor/Torque Converter/Turning
- 6 units — W-251B8 Electric Motor/Torque Converter/Turning
- 2 units — W-251B10 Electric Motor/Torque Converter/Turning
- 4 units — W-251B12 Electric Motor/Torque Converter/Turning
- 8 units — CW-251B10 Electric Motor/Torque Converter/Turning
Why HMS for Off-Highway Powertrain Services
Most drivetrain shops handle whatever comes through the door. Consequently, they apply general knowledge to specialized systems — producing rebuilds that fall short of manufacturer specifications and equipment that fails again before the next scheduled service.
HMS has worked exclusively in off-highway powertrain systems since 1973. Howard Rosenbloom founded the company alongside Milton Tottle, who supported early development and business operations, and Nate Goodman, who managed financial and human resources functions from the start. Furthermore, our leadership team brings credentials that few shops in the country can match — Rocky Morgan with 30+ years of hands-on drivetrain service, Randy Sowers with 24 years as a working mechanic before moving into operations leadership, and Bill Sasser with 27 years of drivetrain parts expertise. We hold ISO 9001:2015 certification, Allison Off-Highway service center authorization, and DNV-GL certification for our Engineering Systems Division.
The HMS team brings to every engagement a base of practical, proven experience with emphasis on quality work, efficient designs, accurate documentation, and open communication throughout every phase of the project. Additionally, with our vast expertise in hydraulic mechanics, HMS can support your starting requirements from inception through installation, test, training, and field support.
Frequently Asked Questions About Off-Highway Powertrain Services
HMS provides a baseline soft overhaul estimate covering standard consumable components — bearings, seals, gaskets, and clutch plates — before teardown begins. After full inspection, technicians identify any additional worn components and provide a supplemental quote. No additional work proceeds without your approval. You always know the cost before we move forward.
HMS operates dedicated transmission and torque converter test stands, hydraulic pump test stands, and an industrial Typhoon Proceco parts washing system at our 20,000 square foot Westville, New Jersey facility. Furthermore, our structured quality control processes are aligned with ISO 9001:2015 certification — every rebuilt component is verified before it returns to service.
HMS has supported drivetrain systems for more than 60 OEM manufacturers across construction, mining, agriculture, material handling, forestry, marine, and power generation industries. Additionally, our turbine starting systems have been deployed on GE LM series gas turbines, Mediterranean Fast Ferries, and in cooperation with General Electric on active power generation projects.
Yes — and this is one of our core capabilities. Many customers operate equipment that is no longer widely supported. HMS maintains technical knowledge, parts sourcing relationships, and engineering capability to service legacy drivetrain systems. Furthermore, our engineering staff can manufacture replacement components to original specifications when OEM parts are discontinued.
Contact HMS by phone at (856) 848-8888 or email sales@hydromechanical.com during business hours, Monday through Friday, 8:00 AM to 4:30 PM Eastern. For parts requests, provide part numbers, equipment make and model, and component identification information. For service requests, our team will assist with intake, logistics, and a baseline estimate before your unit arrives.
Off-Highway Powertrain Services Built on 50 Years of Specialized Experience
Equipment downtime is expensive. Repeat failures are more expensive. Consequently, the right off-highway powertrain services partner holds manufacturer authorizations, tests every unit before it ships, and brings engineering capability that extends from a single rebuilt transmission all the way to a custom turbine starting system for a 150-megawatt application. HMS has operated from the same specialized focus since 1973 — and every component that leaves our facility has been inspected, rebuilt, and tested by technicians who have spent their entire careers on these systems. Furthermore, HMS supports customers from initial diagnosis through installation, training, and ongoing field support — so your equipment stays running long after the rebuild is complete.