Softrak - Kay's Cart
Known at Burnham-On-Sea as 'Kay's Cart' after the benefactor, Mrs. Kathleen Cartwright, whose donation paid for it, the Softrak is the vehicle we use to launch the D class 'Puffin' at all states of the tide and the B class 'Staines Whitfield' at low tide
The Softrak at Burnham-On-Sea was adapted for use by the RNLI by Loglogic. The basic Softrak vehicle was already in production and used extensively by the Forestry Commission and English Nature because of its good ground clearance and very low ground pressure. Its 600 mm Bridgestone Rubber Tracks allow the Softrak to traverse the extremely soft mud conditions we encounter at Burnham-On-Sea with ease. We would not even be able to launch the Atlantic with the MB-4H 2 hours before or after mid tide. If we hit a soft spot with the Softrak on recovery of the Atlantic on the DoDo, we can dump the trailer, drive the Softrak up the beach as the 45 metre towrope is paid out when we will be on firm ground, and keep driving. The grip of the Softrak on firm sand is amazing considering the mud that the DoDo is stuck in!!
The engine is a 63 hp Lombadini water-cooled diesel turbo coupled to a servo controlled hydrostatic transmission system to power the drive. The engine is encased in a water-resistant bay with an automatic drain under the cab. The water-cooling radiator is encased in a stainless steel duct that goes up the right hand side of the cab. This duct also encases the exhaust pipe, air intake and oil cooler. The engine does not have an ordinary key operated starter but utilises a hydraulic starter system to ensure reliable starting in all conditions. High pressure is stored in a gas filled accumulator which supplies oil to the starter motor via a foot operated pedal/valve. The accumulator is recharged once the engine is started via the hydraulic system. A hand pump provides manual backup in an emergency. This high-pressure oil is also used to raise the cab for engine access and the body for cleaning purposes.
The transmission consists of two 600 mm wide rubber caterpillar tracks designed with flexible edges so that the Softrak does not cut into soft ground and are flexible enough to deflect over obstacles. Combined with floating bogies, a smooth ride can be achieved over rough terrain. The track bodies are constructed of high tensile steel and are mounted on transverse cross tubes. The floating bogies are rubber mounted to provide vibration isolation and designed for maintenance free operation. The heavy-duty idler rollers are fully sealed to prevent water and sand ingress and are also maintenance free. The rubber track is tensioned via a ram attached to the front idler, which is pumped up with a grease gun. The overall transmission is driven via a servo controlled hydrostatic system that supplies hydraulic oil to the two speed track motors. Braking is applied automatically when the control lever in the cab is returned to neutral.
The cab has the capacity to carry the driver and two passengers. There are two full size doors, two side opening windows, polycarbonate front and rear screens, and an escape route via the roof. Work lights, sidelights, indicators, wiper, and horn make this vehicle street legal. Blue flashing beacons are supplied for emergency launches.
On the front of the cab is a tow hitch and winch. The winch has a pulling capacity of 3600 Kgs and is operated from a lever in the cab. There is a rear hydraulically raised and lowered quick hitch which is operated from inside the cab. There is a cord attached to the quick hitch from the cab that is used to dump the DoDo and Atlantic when recovering when we get bogged down in the mud at low tides.
Behind the cab, there is a hydraulically tipped body that can carry 8 passengers. There is also the capacity to carry a stretcher or casualty. This is put to good use when we reverse the Softrak into the water to remove casualties from the lifeboats.
Under this body is a 750-litre water tank to aid traction and to supply fresh water to a high-pressure lance used to clean the tracks after a muddy recovery.
To the left of the driver when seated in the cab is a row of levers that control:
- 2 speed track motors
- Parking brake on/off
- Hydraulic hitch raise and lower
- Starter accumulator charging/High pressure water pump
- Winch in/out
By the driver's right hand is the engine and transmission control lever. This single joystick control is unique to Loglogic and controls the Softrak's forward, reverse, left, right directions and engine speed. This control lever has a twist-grip throttle and the joystick is pulled or pushed in the direction we wish to travel. By letting go of the joystick, it returns to a central neural position thus applying the parking brake automatically.
Also, under the right hand door, are two levers for raising and lowering the body and cab.
Softrak Technical Specifications
Engine Lombadini 4 Cylinder Turbo Diesel
Power 67 hp (47 kw)
Capacity 2198 cc
Max Torque 183 Nm @ 1800 rpm
Fully hydrostatic with servo operated pumps and two speed track motors
Pump Capacity 2 x 63 litre/min
Motor Capacity 2 x 750/375 cc
System Pressure 350 bar
Bridgestone rubber track system with fully floating bogies and hydraulic tensioning.
Track Width 600 mm
Max Tractive Effort 3600 Kgs
Ground Pressure 1.25 psi
Maximum Speed 14 kph (9 mph)
Width 2200 mm
Height 2630 mm
Length 3350 mm
Ground Clearance 250 mm
Weight 2900 Kg + 450 Kg Ballast Tank + 750 Kg Ballast