The new 4600 series consists of three tractors, the 80-horsepower 4608, the 90-horsepower 4609, and the 100-horsepower 4610. The series is a replacement for the venerable HD series tractors, though there are differences that make a direct comparison difficult. First, the powerplant used in the 4600 series is markedly different. Whereas the HD series was powered by four-cylinder Perkins engines, Tier IV EPA emissions requirements mandated changes that could not have been incorporated to the design footprint. Massey Ferguson took the opportunity to completely redesign the 4600 series, beginning with all-new three-cylinder AGCO powerplants that make equivalent power (HD Series made 81/91/97 peak horsepower) and are Tier IV compliant without the need for particulate filtration.

Open center hydraulic system
An open center hydraulic system with gear-type pump delivers 65 lpm of total flow to the implement hydraulics, so loader and implement cycling times are faster, increasing productivity.
Independent Rear PTO
The independent rear PTO on every model is engaged electro-hydraulically via a simple twist-knob, and features a wet multi-disc clutch that’s exceptionally durable, to ensure long service life. Two PTO speeds are standard: 540/540E RPM with standard 13/8 inch 6-spline shaft.
Electronic rear 3-point hitch
Our electronic rear 3-point hitch features electronic positioning and draft control. Adjustable lower link arms with extendable category II hook ends have a lift capacity of 2500 kg. An optional high-lift kit increases the lift capacity to 3300 kg. A hand lever in the right hand console gives the 3-point hitch a manual feel while providing electronic precision. All it takes is a simple, intuitive motion to raise or lower the implement. Draft sensing is also standard equipment.

An optional factory-installed loader joystick
The integration of the joystick into the console keeps the design smooth and makes operation easy. And hydraulic valves at the tractor’s mid-point simplify loader connection.
Remote hydraulic valves
The MF4600 Series features two rear remote valves as standard equipment. However, there is an option of up to three rear remote valves for powering implements and attachments. The rear valves are mechanically operated with control levers located in the right hand console.

(Source – http://www.tractor.com/manufacturers/massey-ferguson/2013-massey-ferguson-4608-power-shuttle-cab-tractor-review-1582.html)