The Z997R is powered by a 3-cylinder, liquid-cooled diesel engine with a gross 27.5 kW (37.4 hp) that meets U.S. Environmental Protection Agency (EPA) Final Tier 4 emission standards. The engine achieves Final Tier 4 compliance by using a diesel oxidation catalyst with diesel particulate filter (DOC/DPF) system.

The three-cylinder diesel engine features low noise levels, superior fuel economy, and a high torque reserve that provides plenty of power and performance.

Key features of the engine include:

• Economical, cast-in block cylinder design gives good cooling and long life.
• Liquid-cooled design provides more consistent operating temperatures than air-cooled.
• Direct fuel injection is provided. 
  • Injects fuel directly on top of pistons for more efficient combustion
  • Develops more horsepower per gallon of fuel
  • Improves starting
• Aluminum alloy pistons with built-in steel struts are lightweight to reduce connection rod bearing loads and provide good heat-transfer characteristics.
  • Design permits tighter tolerances and neutralizes expansion of the piston, thereby reducing blow-by fuel and noise from the piston slap
  • Higher top rings on the piston and a thinner head gasket greatly reduce the volume of unburned waste and increase combustion efficiency
• Timing gears and injector drive gears utilize helical profile gears to help lower engine noise.
  • Gear teeth have a newly designed ”roll-off” profile, giving almost no clash, no noise, and no backlash
• Fuel filter with replaceable element is provided.
• Full-pressure intake manifold provides quick starts in temperatures down to -18°C (0°F).
• Auto-bleed fuel system gives extra convenience. 
  • No need to prime the system if the unit runs out of fuel; the system will self-prime the injection pump, lines and injectors, providing fast fuel recovery
• Key start and shutoff eliminate fuel shut-off knob; electric solenoid shuts fuel supply off immediately when key is turned off.
• See-through coolant recovery tank permits operator to check coolant level without removing radiator cap.
• Sealed radiator compartment keeps trash and debris on outside of hood.
• Dual-element, dry-type air cleaner with safety element and air service indicator is provided. 
  • Dual-element design for added engine protection
  • Easy to service
  • Completely sealed for effective cleaning and 90 to 95 percent of dirt ejected before it reaches the paper element
  • Secondary safety element for additional filtering
  • Air-restriction indicator to let operator know when the filter needs servicing
• Full-pressure lubrication with full-flow filter lengthens engine life. 
  • Engine wear reduced by ensuring proper lubrication, even when operating on hillsides or uneven terrain
  • Oil filter helps keep oil clean for increased engine life
• Automotive-type alternator (75 amp) provides plenty of charge to the battery.
• Rear-mounted, covered radiator and fan keeps noise away from the operator and is easy to service.
• Isolated engine mounting reduces engine vibration at operator’s station for more comfortable operation.

There are three side-discharge mower-deck options available for the Z994R Diesel ZTrak™ Mower:

• The 60-in. (152-cm) 7-Iron PRO Side-Discharge Mower Deck is suited to a variety of mowing jobs, including trimming and grooming.
• The 60-in. (152-cm) 7-Iron PRO Mulch On Demand™ Mower Deck can be converted from a wide-open, side-discharge mode to a fully chambered mulching mode with a single move of a lever.
• The 72-in. (183-cm) 7-Iron PRO Side-Discharge Mower Deck is suited to a variety of mowing jobs, including trimming and grooming.

For professional landscapers and government municipalities requiring rear discharge placement of grass and debris, John Deere FastBack PRO rear-discharge mower decks deliver a commercial zero-turn mowing solution for both gas and diesel machines. Advantages of a rear-discharge mower include:

• Less chance of damage from objects being thrown from the mower deck
• Time savings with the ability to mow closely around fixed objects with either side of the deck
• A cleaner mowing experience by lessening the amount of debris that can blow onto the operator

A rear-discharge mower deck is ideally suited for:

• Schools
• Parks
• Playgrounds
• Traffic areas (city boulevards, roadsides, etc.)
• Areas with long, grassy spots that need to be cut, where you are not as concerned about wide dispersal of grass (park areas, roadsides, etc.)

The durability features of the frame are as follows:

• Heavy-duty, thick-gauge, steel channel mainframe for strength and durability
• Cast I-beam caster arms to handle the beating and pounding professional mowers receive
• Wide-open access for maintenance and cleaning

The hydrostatic drive features two 13-cc (0.8-cu in.) unitized hydraulic pumps combined with commercial-grade, heavy-duty wheel motors into a single unit.

One pump and one motor drive each wheel on the ZTrak™ E and M Series Mowers. This provides several benefits:

• Exceptional cooling in high-load conditions
• Easy-to-check level and refill hydraulic oil
• Opens up access under the seat

John Deere provides the commercial mower industry with the Michelin X Tweel Turf technology for Commercial ZTrak Mowers:

• 24x12N12 as an ordering option code for ZTrak Petrol Mowers with 48 in., 54 in., 60 in., and 72 in. (137-cm, 152-cm, and 183-cm) Mower Decks
  • 24x12N12 is also available as base code equipment for ZTrak Petrol Mowers with 48 in., 54 in., 60 in., and 72 in. (137-cm, 152-cm, and 183-cm) Mower Decks (ordering information available at Configurator on the Tweel model page)
• 24x12N12 as an ordering option code for ZTrak Z994R Diesel with 54 in., 60 in., and 72 in. (137-cm, 152-cm, and 183 cm) Mower Decks
• 26x12N12 as an ordering option code for Z997R Diesel with 60 in. and 72 in. (152-cm and 183-cm) Mower Decks

Michelin is a world leader in tyre manufacturing and technology. This airless radial tyre solution is an industry first for John Deere, which provides an additional advantage to John Deere customers.