The M+S MLHT Series is a disc valve orbital motor - the highest-torque, highest-pressure class of orbital motor M+S build. Instead of the spool valve used in a Gerotor or Geroler motor, a hardened rotating disc valve is held against its seat by hydraulic pressure. The seat is pressure-balanced and self-compensating, so it keeps sealing as it wears. That is what lets these motors run higher inlet pressures for longer, hold their volumetric efficiency for years and deliver full torque down to a crawl.

MLHT is the US-standard build of the MT disc valve frame: an SAE C 4-bolt mount on a 127 mm spigot, a 1-1/2 inch keyed shaft, and 1-1/16 inch UNF O-ring boss working ports with a 9/16 inch UNF case drain. It is the interchange for the US Danfoss OMT. Eight sizes, 161 to 724 cm3/rev, 210 bar inlet, up to 1300 Nm continuous.

If the machine was built for the North American market and the motor sits on an SAE C face with O-ring boss ports, this is the frame - not the European MT.

Applications

• UNO-ported replacements for Danfoss OMT (US) drives
• Heavy winch and hoist packages
• Slew drives on cranes and material handlers
• Drill and auger heads on piling rigs
• Drum, feeder and conveyor drives on plant

Cross-Reference - Compatible Equivalents

Verified against the M+S factory motor index and cross-reference chart. Type any competitor part code into the cross-reference tool on our Hydraulic Motors category page and it will identify your equivalent instantly.

Standard Supply Configuration

• SAE C mount, four holes, 127 mm spigot
• 1-1/2 inch straight keyed output shaft (C)
• 2 x 1-1/16-12 UN O-ring boss working ports, side entry (port code 4)
• 9/16-18 UNF case drain
• High pressure shaft seal (U) - 210 bar inlet rating
• Manganese phosphate finish as standard from the factory

How to Order - Part Number Breakdown (Nomenclature)

Read left to right. Example: MLHT 315 C4U

★ = the configuration we hold and sell from the dropdown above. Factory note: port version 7 is not available on S (short) motors. Codes outside the dropdown are factory builds - use the quote form and we will price them for you.

General Performance Data

Download the M+S MLHT Series Factory Datasheet (PDF)

Technician's Advice

When do you need a disc valve motor? When the job is heavy and continuous - conveyor and auger drives, agitators, winches, drum and mixer drives, road-sweeper brushes, feed mixers, forestry heads, drilling rotation. If the motor spends its day near the pressure limit or turning slowly under full load, the disc valve frame is the one that survives. For light intermittent duty a Gerotor or Geroler motor costs less and does the job.

Case drain. Always run the case drain back to tank on its own line, with the lowest practical back pressure and no shared return. A blocked, teed or missing drain line is the number one killer of shaft seals on every orbital motor ever made - and on a high-pressure disc valve unit it will blow a seal in minutes, not months.

Running in. Fill the case with clean fluid before you start it. Run 5 to 10 minutes at moderate load and moderate speed before you go to full pressure. Never crack a motor to full relief on the first turn.

Shaft loads. These frames run tapered roller bearings, so they will take genuine radial load from a sprocket, pulley or chain drive - but check the permitted overhung load and its distance from the flange face in the datasheet before you hang a drive off it. Overhung load is the second most common failure we strip down.

Filtration and fluid. Keep the system at ISO 4406 20/18/15 or cleaner and the fluid between 20 and 60 cSt at running temperature. Disc valve motors are more tolerant than a piston motor, but grit still laps the valve face flat.

O-ring boss ports. The 1-1/16-12 UN ports seal on an O-ring against the port face. No tape, no sealant, and do not chase a weep with more torque - back it out and inspect the O-ring and the seat.

MLHT or MT? Identical gear set and performance. MLHT for SAE C face and UNF ports, MT for the square 4-bolt European face with BSPP ports.

Seal kits: MLHT-SKU - see the seal kit listing below.

Warranty and Service

12-month warranty on every motor. Identifying an existing motor? Photograph every part number and stamped character on the motor body and housing and send them through with your enquiry - we identify orbital motors from photos every day.

Buy the Seal Kit for This Motor

See How an Orbital Motor Works and Fails

Recorded in our own service workshop - we rebuild these for a living.

Shipping and Freight Information

We ship Australia-wide. Orders are dispatched from our supply network in Melbourne, Brisbane and Perth, so your parts leave from the warehouse closest to you on express freight. Disc valve motors are heavy - a single unit runs from 10 kg to over 37 kg - so freight reflects real weight and real distance. We do not hide freight in inflated product prices.

Estimated delivery timeframes:

• Standard parcels: 2-7 business days
• Heavy freight: 3-8 business days
• Orders placed before 12 Midday AEST ship same business day where stock is available

Why Buy From Us

• 20+ years of hydraulics expertise - we know what we are selling
• Australian owned and operated - Gold Coast, QLD
• ABN: 92 969 264 674 - registered Australian business
• Secure checkout - Visa, Mastercard, PayPal, Zip Pay, Direct Deposit
• Tax invoices supplied with every purchase
• Messages answered within normal business hours - 8:00am to 5:00pm Monday to Friday
• Phone: 07 5563 1982 or 1300 1 HOSES
• Email: sales@mhfgc.com.au

Out of Stock Policy

It is our intention to maintain active stock on every listed item at all times. On rare occasions a size may be temporarily unavailable. If this occurs you will be notified immediately and offered the choice of a full refund or a short wait for incoming stock - typically 3 to 14 days.

Before you order. Seal kits follow the mount and the seal you choose, not just the series. This range uses MLHT-SKU. Give us your full motor code and we will send the right kit.