The drum drive on a transit mixer is the mechanism that turns the concrete drum. On Indian machines it takes one of three forms: a PTO drive, which taps power from the truck’s own engine through a power take-off; a REPTO drive, where that power is taken from the rear of the engine instead of the gearbox; or a slave engine, a small separate diesel engine of roughly 52 to 109 HP (39 to 81 kW) bolted to the mixer itself. The choice decides what happens to your concrete when the truck engine stops, what you service every few hundred hours, and how much weight you carry to every pour.

Last updated: August 2026. Every specification below is taken from our listings at the time of writing, for the standard build of each model.

What drives the drum on a transit mixer?

The drum on a transit mixer never stops turning between the batching plant and the site. That slow rotation is what keeps the concrete moving so it does not settle and set on the way. Something has to supply the power for it, and that something is the drum drive.

In every case the actual turning is done by hydraulics. A pump sends oil under pressure to a hydraulic motor at the front of the drum, and a gearbox at the drum head turns the pump’s speed into the slow, heavy rotation the drum needs. What changes from machine to machine is the engine that turns the pump.

Two sources are possible. Either the pump is driven by the truck’s engine, through a power take-off, or the mixer carries its own small engine for the job. Power take-off is almost always shortened to PTO on a spec sheet, and the separate engine is called a slave engine, an auxiliary engine, or simply a separate engine drive, depending on which company wrote the brochure.

That is the whole decision. Everything else — fuel burn, what you service, what happens in a breakdown — follows from it.

What is a PTO drive on a transit mixer?

A PTO, or power take-off, is an output on the truck’s gearbox that lets you run something other than the wheels from the same engine. On a transit mixer it drives the hydraulic pump that turns the drum.

The advantage is that there is one engine on the vehicle, not two. One engine to fuel, one air filter, one oil change, one set of belts. Nothing extra sits on the chassis except the pump and the pipework, so the mixer unit stays lighter and the driver has one less thing to start.

The limitation follows from the same fact. If the truck engine is off, the drum is not turning. In a traffic jam that does not matter, because the engine is idling anyway. It matters when a truck breaks down loaded, when a driver switches off at a gate to save fuel, or when the gearbox itself is out of service — the concrete then sits still in a warm drum with a clock running on it.

On the units listed in India, the plain PTO drive turns up on the Universal 6 m³ mixer and the Conmat MR 80C, and AJAX lists its 10 m³ AF 10XP as a truck PTO drive.

What does REPTO mean on a mixer truck?

REPTO stands for rear engine power take-off, and it is a PTO taken from the back of the engine itself rather than from the gearbox. You will see the letters in the model name of factory-built mixer trucks, such as the Tata Signa 2830.K 8 Cum REPTO RMC, whose specification describes a REPTO platform built for ready-mix concrete mixing and auxiliary systems.

Taking the drive off the rear of the engine rather than the gearbox means the drum’s power path does not run through the transmission. In practice that is what lets the drum keep turning steadily while the truck is standing at a gate or crawling in traffic, without the mixing speed following whatever the gearbox is doing.

REPTO machines are complete trucks, sold and registered as one vehicle: the 28,000 kg gross vehicle weight, 8 m³ mixing body and 9-speed gearbox of that Tata Signa are all one specification. That is different from the mixer units in the section below, which are drums built to be mounted on a chassis you buy separately.

Ten factory-built mixer trucks are currently listed in India, from a 7 m³ body on the Mahindra Blazo X 28 at 28 tonnes GVW up to 9 and 10 m³ bodies on the Ashok Leyland AVTR 3825 8×4 RMC at 35 tonnes. Browse the current truck-mounted transit mixers to compare bodies and chassis together.

What is a slave engine on a transit mixer?

A slave engine is a small diesel engine mounted on the mixer unit whose only job is to drive the hydraulic pump for the drum. It has its own fuel supply, its own starter, and its own service schedule. Some brochures call it an auxiliary engine or a separate engine drive; on AJAX’s AF 6XE, AF 7XE and AF 8XE units the spec sheet says separate engine drive, and it means the same thing.

Slave engines on the mixers listed here are small. They run from 52 HP (39 kW) on the 3 m³ and 4 m³ Schwing Stetter AM 3 and AM 4, through 70 HP (52 kW) on the common 6 and 7 m³ sizes, up to 108.6 HP (81 kW) on the 9 m³ Sunbeam 85 XL. Set that against a mixer truck’s main engine of 250 to 300 HP and the scale is clear: the slave engine is sized for the drum alone.

What you buy with it is independence. The drum turns whether the truck is running or not, so a load can be kept moving while the vehicle is stopped for any reason, and the same mixer unit can go onto a chassis without a suitable PTO. Fleet operators who mount drums on trucks they already own often choose it for that reason alone.

What you pay for it is a second engine. Another set of filters, another oil change, another starting battery, more weight on the chassis, and a machine that will not mix if the small engine fails even though the truck is fine. The hour-by-hour service schedule for a slave-engine mixer covers two engines, not one.

A few makers avoid the choice altogether. The Macons M6TM is listed with a hydrostatic drive at 110 HP (82 kW), and Venus lists its 6 and 7 m³ units by the hydraulic makes they use — Rexroth, PMP or Eaton — rather than by the engine behind them.

Which drum drive do Indian transit mixers use?

Most mixer units sold in India as a drum for your own chassis are offered with a choice, not a fixture. Of the 31 standard transit mixer units currently listed, 16 are specified as PTO or slave engine, or as slave engine with a PTO option — the buyer decides at order time.

Table: drum drive on standard transit mixer units in India — as per current August 2026 specifications

Drum drive as listed Units Examples Drum speed
PTO or slave engine (buyer’s choice) 11 Schwing Stetter AM 3 to AM 12, Conmat MR 60C, MR 70XL 0–12 / 0–14 rpm
Slave engine with PTO option 5 Sunbeam 65, 65 XL, 75, 85, 85 XL 0–14 rpm
Slave engine only 3 Putzmeister P7+, Conmat MR 70C, Sunbeam 45 0–14 rpm
Separate engine drive 3 AJAX AF 6XE, AF 7XE, AF 8XE 0–12 rpm
EPTO (engine power take-off) 3 Putzmeister P8, P9 and P10 PTO 0–14 rpm
PTO only 2 Universal, Conmat MR 80C 0–14 rpm
Truck PTO 1 AJAX AF 10XP 0–12 rpm
Hydrostatic 1 Macons M6TM 0–14 rpm
Listed by hydraulic make 2 Venus 6.0, Venus 7.0 0–14 rpm

The Putzmeister P9 PTO shows what an engine-driven machine looks like on paper. Its sheet lists 279 HP (208 kW) against engine power, which is a truck-sized figure, because an EPTO machine has no mixer engine of its own — the number is the vehicle’s. A slave-engine unit of the same 9 m³ class would show something closer to 100 HP, and the truck’s engine would be listed separately.

Empty weights sit between 3,060 kg for a 4 m³ Sunbeam 45 and 5,550 kg for a 12 m³ Schwing Stetter AM 12. The chassis each one needs is on the same sheet: 22 of the 31 units are specified for a 3-axle truck, the 3 and 4 m³ units for a 2-axle truck, and the five largest Schwing Stetter drums from 9 m³ upward for a 4-axle chassis. Compare the full range of standard transit mixer units before you commit a chassis to one.

How fast does a transit mixer drum turn?

Every standard mixer unit listed in India runs its drum from zero to either 12 or 14 rpm. Rpm means revolutions per minute — how many full turns the drum makes in a minute. Fourteen rpm is roughly one turn every four seconds, which looks slow from outside and is fast for the concrete inside.

The drum uses that range in three ways. Loading at the plant takes the top of the range, because the blades inside the drum act as a screw and pull the concrete in when the drum spins one way. Travelling uses the bottom, usually two to four turns a minute, which is enough to stop the mix from separating without churning it. Discharge reverses the direction so the same blades push the load out down the chute.

This is why the drive matters on the road and not just at the plant. Whatever supplies the power has to hold that slow rotation for the whole journey. On a PTO machine that means the truck engine runs for the whole journey too.

Which drum drive costs less to run?

No manufacturer publishes a fuel comparison between a PTO drive and a slave engine, and any number you see quoted for one is worth treating carefully. What can be compared is what each arrangement adds to your costs, and that is straightforward enough to work out for your own operation.

A slave engine adds a second service line item. Engine oil and filter, air filter, fuel filter and a battery, at that engine’s own interval, on top of everything the truck already needs. It also adds its own fuel draw while the drum turns and burns nothing when the drum is idle and the truck is moving under its own power.

A PTO drive adds none of that, but it loads the truck engine whenever the drum turns, including every minute the vehicle stands at a gate with concrete on board. On a long site queue that is the truck’s main engine idling under load, and its fuel goes on the truck’s account rather than the mixer’s.

Which one wins depends on how your trucks actually spend their day. Long runs with short waits favour the PTO drive. Long waits, split shifts and drums that get mounted on more than one chassis over their life favour the slave engine. Neither difference is large enough to override the practical questions in the next section.

Ready to compare machines? Browse the current range of concrete mixers and transit mixers and speak to a dealer about which drive their chassis supports.

What should you check before buying a transit mixer?

Start with the chassis, because it settles the drive. If you are buying a drum to mount on a truck you already own, ask the dealer whether that gearbox has a PTO output rated for a mixer duty. Where it does not, the slave engine stops being a preference and becomes the only option.

Then check these, in this order:

  • Drum capacity against your chassis rating. A 6 m³ load of concrete weighs about 14,400 kg on its own, before the drum’s own 3,750-odd kg. Both figures sit on the spec sheet as separate lines — add them and read the total against what the chassis is registered to carry.
  • Who services the slave engine. It is often a different make from the truck. Find out where the nearest service point is before you find out the hard way.
  • Whether the drum turns with the truck off. Ask for a demonstration. On a PTO machine it will not, and you should know that before your first breakdown, not during it.
  • Water tank and washout arrangement. Tanks on these units run from 300 to 650 litres, with 450 litres by far the most common; a drum that cannot be washed at the end of a pour hardens from the inside out.
  • Drum speed range on the sheet. Zero to 12 or 14 rpm is standard. Anything that cannot reverse for discharge is not a transit mixer.

If you are still choosing between machine types rather than drives, the comparison between a self-loading mixer and a transit mixer is the better place to start, and the guide to concrete mixer types covers the wider family. Where the concrete has to go up rather than along, a concrete pump does the placing and the mixer only delivers.

Transit mixer drum drive, in short

The drum on a transit mixer is turned by hydraulics, and the drum drive is simply the answer to which engine turns the pump. A PTO or REPTO drive uses the truck’s engine, keeps the machine light and gives you one engine to look after, but the drum stops when the truck does. A slave engine of 52 to 109 HP gives the drum its own power and its own independence, at the cost of a second engine to fuel and service.

Most mixer units sold in India are offered either way, so this is a decision you make at order time, on the basis of your chassis and how your trucks spend their day. Read it off the spec sheet before you sign: on our listings it is the line marked drum drive, and it tells you more about daily operation than the capacity figure beside it.

For the full picture of how these machines work on Indian sites, the guide to concrete mixer trucks and how they work in India covers capacity classes, the workability clock and what they cost. Greasing points and intervals apply to the drum rollers and the drive gearbox as much as to any other machine on your yard.

Looking for a transit mixer? See live transit mixer models and specifications and get a quote from a dealer near you.

Prices, specifications and features are indicative, vary by variant, location and date, and should always be confirmed with the official OEM or authorised dealer before any purchase decision. DesiMachines is not liable for decisions taken on the basis of information that may have changed after publication.