Abstract: A rotary tilling device has a cutting device having a plurality of cutters each of which is rotatably mounted on a supporting member. The cutter has a vertical portion and a lateral portion at an end of the vertical portion and has edges on both sides of the vertical and lateral portions. The cutter is held by a stopper in a tilling position when rotated in a tilling direction, and is released in a grass cutting position when rotated in the opposite direction.

Abstract: A rotary tilling device has a cutting device having a plurality of cutters each of which is rotatably mounted by a bolt on a supporting member at a base end thereof. The cutter has a vertical portion and a lateral portion at an end of the vertical portion and has edges on both sides of the vertical and lateral portions. A stopper for receiving the cutter in a tilling position and a spring plate for resiliently holding the cutter in the tilling position are provided on the supporting member.

Abstract: A rotary tiling device has a cutting device having a plurality of cutters each of which is mounted on a supporting member at a base end thereof in such a manner that the cutter is rotatable about a first center. The cutter has a vertical portion and a lateral portion at an end of the vertical portion and has edges on both sides of the vertical and lateral portions. The base end has an arcuated periphery about a second center. The first center is offset from the second center, so that in grass cutting operation, the arcuated periphery is positioned in a position which is further outward than its position in the soil cutting operation.

Abstract: A cultivator has a blade downwardly projected from a frame, an injector provided at a lower portion of the blade, a compressor mounted on the frame and an air tank for storing air compressed by the compressor. An unloading valve provided in a hydraulic circuit for supplying compressed air in the air tank to the injector. The unloading valve is arranged to be opened when the pressure in the air tank is higher than a predetermined value. A master valve is provided in the circuit means, for passing the compressed air to the injector. A mechanical valve is provided to be opened when the depth of the injector reaches a predetermined value, so that the compressed air is supplied to the master valve to open it, whereby air is injected from the injector when the pressure in the air tank is higher than the predetermined value at the predetermined position of the injector.