Kubota B7100HST

The Kubota B7100HST is a compact utility tractor, manufactured by Kubota Corporation since 1977 to 1984. The B7100HST tractor is equipped with Kubota D750-AH vertical diesel engine with 0.75 L (742 cc, 46.5 cu-in) of displacement and hydrostatic transmission with infinite 2-range forward and 2-range reverse gears.

The Kubota B7100 HST utility tractor used a three-cylinder liquid-cooled diesel engine Kubota D750-AH with 742 cc (46.5 cu-in) of displacement. This motor has 68.0 mm (2.68 in) of the cylinder bore and 70.0 mm (2.76 in) of the piston stroke. Compression ratio rating is 22.0:1. The engine produced 16.2 PS (11.9 KW; 16.0 HP) at 2,800 rpm of horsepower and 43.1 Nm (4.4 kg·m; 31.81 lbf·ft) at 1,800 rpm of torque.

The Kubota B7100 HST is equipped with a hydrostatic transmission. This transmission has 2-range forward (5.6-14.5 km/h, 3.5-9.0 mph) and 2-range reverse gears (3.9-10.0 km/h, 2.4-6.2 mph).

The Kubota B7100 hydro is avalible in two versions:

• Kubota B7100HST-E – two-wheel variant 4×2 2WD
• Kubota B7100HST-D – four-wheel variant 4×4 MFWD 4WD

The tractor used manual steering, brakes with a differential mechanical expanding shoe, сlosed center center hydraulic system and foot pedal operated the differential lock. The B7100 HST model has an open operator station or a two-post fixed rollover protective structure (ROPS) available as an option.

General specifications

Engine

The Kubota D750-AH is a compact, three-cylinder diesel engine designed for reliability and efficiency in a variety of industrial and agricultural applications. This four-stroke, vertical engine boasts a displacement of 742 cubic centimeters, achieved through a cylinder bore of 68 mm (2.68 in) and a piston stroke of 70 mm (2.76 in). With a high compression ratio of 22:1, it ensures efficient combustion typical of diesel engines.

Delivering a maximum gross power of 16.2 PS at 2,800 rpm, and a power output at the PTO shaft of 13.2 PS, the engine is capable of producing a strong torque of 43.1 Nm at 1,800 rpm. This balance of power and torque makes it particularly suitable for applications requiring steady, reliable performance under load.

The combustion chamber is of a spherical design, which helps promote efficient fuel-air mixing. Fuel is delivered through a Bosch K Type Mini Pump using an indirect injection system with a Bosch throttle-type nozzle. Injection timing is carefully set at 25 degrees before top dead center to optimize combustion efficiency and power delivery. The engine follows a firing order of 1-2-3, providing smooth operation typical of a three-cylinder configuration.

Cooling is managed by a pressurized radiator system with forced water circulation via a water pump, maintaining an ideal operating temperature between 80.5 and 95 degrees Celsius. The engine holds about 4.6 liters of coolant to ensure consistent thermal management during operation. Lubrication is provided through a forced lubrication system using a pump and a full-flow paper cartridge oil filter to maintain oil cleanliness and engine longevity. With an oil capacity of 3.9 liters, the system maintains adequate oil pressure ranging from 68 kPa at idle to over 196 kPa at rated speeds.

Starting the engine is facilitated by a 12-volt electric starter motor, supplemented by glow plugs to ensure reliable cold starts, particularly in lower temperatures. Speed regulation is handled by a centrifugal mechanical governor that maintains steady engine speeds under varying loads. The PTO shaft rotates counterclockwise when viewed from the shaft side, which is important for machinery compatibility.

Overall, the Kubota D750-AH represents a thoughtfully engineered diesel engine combining power, efficiency, and durability. Its robust construction, advanced fuel injection system, and effective cooling and lubrication mechanisms make it a dependable choice for demanding applications requiring consistent performance.

Transmission and chassis

The Kubota B7100 series features a rugged and versatile chassis designed to suit different driving needs. The B7100HST-E model comes with a 4×2 two-wheel-drive setup, ideal for lighter tasks and operations on relatively even terrain. Meanwhile, the B7100HST-D is equipped with a 4×4 mechanical front-wheel drive system, providing four-wheel-drive capability for improved traction and performance on rougher or slippery surfaces.

Steering is manual, giving the operator direct and responsive control over the vehicle’s direction. To enhance stability and traction during demanding tasks, the rear differential is equipped with a mechanical lock, allowing the rear wheels to turn at the same speed and prevent slippage.

The braking system utilizes differential mechanical expanding shoes, which provide reliable stopping power tailored to the vehicle’s drivetrain. This brake type is known for durability and consistent performance in rugged conditions.

Power delivery is managed through a hydrostatic transmission, which offers smooth and variable speed control without the need for frequent gear changes. The transmission provides two forward and two reverse gears, allowing the operator to select appropriate speeds depending on the task. Forward speeds range from 5.6 to 14.5 kilometers per hour (approximately 3.5 to 9.0 miles per hour), while reverse speeds range from 3.9 to 10.0 kilometers per hour (about 2.4 to 6.2 miles per hour). This range of speeds ensures the tractor can handle a variety of jobs from slow, precise maneuvering to faster transit between work sites.

Overall, the transmission and chassis design of the B7100 series offer a balance of control, traction, and flexibility, making these tractors well-suited for both general farming duties and more challenging terrain.

Tires

PTO and 3-point linkage

The Kubota B7100 series is equipped with a rear power take-off (PTO) system, which is integral for powering various implements like mowers, tillers, and other attachments. The rear PTO is a transmission-driven type, which means it’s mechanically linked to the engine through the tractor’s transmission system, allowing for efficient power transfer. The PTO speed is versatile, with options for 540, 750, or 1,000 rpm, offering flexibility for different implements that require specific operational speeds. Additionally, the rear PTO can run at 2,500 rpm for high-speed applications, while the front PTO is capable of reaching up to 2,800 rpm, providing high power output for front-mounted attachments.

In terms of lifting and attachment capabilities, the B7100 series features a Category I 3-point linkage system, which is a standard for compact tractors. This linkage system allows for easy attachment and detachment of implements such as plows, harrows, and other farming tools. The hydraulic lift system ensures that the 3-point linkage can raise and lower attachments smoothly and efficiently, with a maximum lifting capacity of 181 kg (400 lbs) at the link ends. This lifting capacity makes the B7100 versatile enough to handle a range of light to moderate-duty implements, making it suitable for a variety of agricultural tasks.

Hydraulic system

Attachments

Serial numbers