Caproni 20MR Group 2 Gear Motor 4.5 to 28cc - 4 Bolt DIN Mount, 1:8 Tapered Shaft

The Caproni 20MR Series is a group 2 external gear motor built in Europe by Caproni. Gear motors are the cheapest reliable way to turn oil flow into shaft rotation at medium to high speed — no orbital gear set, no disc valve, just two meshing gears in a precision housing. They are compact, light, and they will run all day at 2,000 to 3,500 rpm without complaint.

Pick your displacement and your mount and shaft below and the exact factory part number appears on screen. Every option in the dropdowns is a real catalogued part number with a firm price — nothing here is a guess.

Applications

• Radiator and oil cooler fan drives
• Sawmill and docking saw drives
• Sprayer pump, blower and vacuum drives
• Conveyor and auger drives where speed beats torque
• Group 2 drive replacements on European-built machinery

Ways to buy this gear motor

• Off the shelf: every displacement and mount combination in the dropdowns below
• Seal kits and shaft seals: GM2-SKV, GM2-SKT — on the seal kit listing linked further down
• Rotation: these motors are supplied in the standard rotation. Reverse rotation (CCW) builds are available — tell us in the order notes or call and we will confirm before we ship
• Matching gear pumps: we stock the Caproni pump range in the same group — see the gear pump category
• Anything not in the dropdown (rear ports with drain, anti-cavitation check valve, non standard shafts) is a factory build. Call 1300 146 737 or use the enquiry form and we will price it.

Pick your displacement, mount and shaft

Other mounts and shafts in this range

This page is the DIN Mount, 1:8 Taper build. The same 20MR motor in the other factory configurations:

Standard Supply Configuration

• Bare motor, bi-directional rotation — no valve block, fittings or adaptors fitted
• BSPP inlet, outlet and case drain ports, sizes per the specification table for your displacement
• Mounting flange and output shaft exactly as selected in the dropdowns above
• Shaft seal is rated for case pressure only — the case drain must be plumbed back to tank on its own line
• Supplied as a single motor; seal kits are listed separately

Specifications

4 Bolt DIN Mount - 1:8 Tapered Shaft

How to choose

• Work out the speed you need first. rpm = (flow in L/min × 1000) ÷ displacement in cc, then knock off about 10 percent for slip. Gear motors like speed — if the answer is under about 500 rpm you want an orbital motor, not this.
• Then check the torque. Nm ≈ (displacement in cc × pressure drop in bar) ÷ 62.8, times about 0.85 for mechanical efficiency. If the number is short, go up a group rather than up a displacement.
• Match the mount to what is already on the machine. 4 bolt DIN with a 1:8 taper is the European standard and takes a taper hub. SAE 2 bolt with a keyed or splined shaft is the American standard and is what most Australian gearboxes and couplings expect.
• Not sure? Call 1300 146 737 with your pump flow, your pressure and what you are driving. We do this every day.

Technicians Advice

A gear motor is not a gear pump run backwards. People try it every week and wreck them. A motor has a case drain and a shaft seal rated for low pressure only; a pump has neither. Run a pump as a motor and the first thing that happens is the shaft seal lets go. Run a motor as a pump and it will do it, badly, until the bearings give up. Buy the right one.

The drain line decides how long it lives. The case port must go back to tank on its own line, full bore, no restrictors, no tee-ing into a pressurised return. The drain pressure limit on these is 6 bar — that is nothing. If you have to run a long drain line, go up a hose size.

Overrunning loads will cavitate it. Gear motors have almost no internal resistance, so anything with inertia — a flail head, a saw blade, a fan, a loaded conveyor — keeps driving the motor after you close the valve. It sucks air past the shaft seal and pits the gear faces. Fit an anti-cavitation check valve or a crossline relief. Vivoil offers the check valve as a factory option on the group 2 and group 3 frames; ask us.

Taper shafts: clean both surfaces dry, no grease, no anti-seize, and torque the nut properly. A taper hub that has been assembled greasy will work loose and then chew the taper, and the taper is part of the motor.

Do not overspeed the small ones. The group 1 frames will spin to 5,000 or 6,000 rpm but they also have a minimum speed around 700 rpm — below that a gear motor barely makes torque and runs rough. That is not a fault.

Warranty and Service

12-month warranty. If you are identifying an existing motor, photograph every number cast or stamped on the body and send it through with your enquiry — gear motor part numbers are long and one letter changes the shaft.

Buy the Seal Kit for This Motor

Complete your setup

Buy the Seal Kit for This Motor

Fitting out a fleet or buying several? Call us and we will work out freight and lead time on the whole lot.

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. Because we sell solid steel components, freight costs reflect real weight and real distance. We do not hide freight costs in inflated product prices. What you see is what you pay.

• Standard parcels: 2 to 7 business days
• Heavy freight: 3 to 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
• Australian owned and operated, Gold Coast QLD
• ABN 92 969 264 674
• Secure checkout: Visa, Mastercard, PayPal, Zip Pay, Direct Deposit
• Tax invoices supplied with every purchase
• 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.

Need help choosing? Call 1300 146 737 or email sales@mhfgc.com.au — real technicians, real answers.