Please select the most similar patent number from A, B, C and D. Which number is?
A palm ratchet tool comprises an upper cover (1), a lower cover (4), a ratchet (3), a pawl rocker shifter (5), and bits (2). The upper cover is provided with multiple through holes (11). The multiple bits are respectively disposed in the through holes. The pawl rocker shifter is disposed between the upper cover and the lower cover. The pawl rocker shifter comprises a left pawl (51), a right pawl (52), and a rocker (53) connected to the left pawl and the right pawl. The lower cover is connected to the bottoms of the bits. The top end of the rocker penetrates through the lower surface of the lower cover. The ratchet is disposed on the periphery of the upper cover and the lower cover. Ratchet gear teeth (3) are disposed on the inner surface of the ratchet. When the pawl rocker shifter approaches the ratchet, the left pawl or the right pawl meshes with the gear teeth under the action of the rocker.
A: A double-ratchet type one-way clutch. Pawls (3) do not knock the surfaces of ratchets when the double-ratchet type one-way clutch rotates in the idling direction. The double-ratchet type one-way clutch mainly comprises: a driving ratchet (1), a driven ratchet set, a pawl set, and rolling bearings (10, 11). The pawl set comprises: a pawl base cover (5), a plurality of pawls (3), and a plurality of elastic elements (4). The driven ratchet set comprises: a driven ratchet set ratchet (2), balls (6), a ball cage (7), and a driven ratchet set supporting ring (8). When the double-ratchet type one-way clutch rotates in the idling direction, the driving ratchet (1) firstly rotates relative to the driven ratchet set ratchet (2), to make the top land of the driven ratchet set ratchet (2) and the top land of the driving ratchet (1) complementary in the axial direction; and then the driving ratchet (1) drives the driven ratchet set ratchet (2) to rotate together, so that the pawls (3) slide over the tail end of the top land of the driving ratchet (1) and then reach the top land of the driven ratchet set ratchet (2), thereby preventing the pawls (3) from knocking the driving ratchet (1).
B: Disclosed is a ratchet tooth engagement device for a ratchet tool, comprising a ratchet wrench body (1), an assembling hole (11) penetrating through one end thereof; and a detent assembly (2), which is mounted in the assembling hole (11) of the ratchet wrench body, and comprises a ratchet base (21, 5), a ring gear disc (22, 6), an elastic element (7, 23), and a seal cover (24). A driving hole is provided in and penetrates through the ratchet base from the top to the bottom, a ring portion (212, 52) protrudes from the outer peripheral side of the ratchet base, and a tooth row (3, 9) is provided around either side or both sides of the ring portion (212, 52), the tooth row (3, 9) being engaged with row teeth (10) provided on the ring gear disc (22, 6) sheathed on the ratchet base. The seal cover (24) is sheathed on an end portion of the ratchet base (21, 5) and covers the opening of the assembling hole (11). The elastic element is sheathed to the end of the ratchet base provided with the ring gear disc (22, 6), and two ends of the elastic element (7, 23) are respectively elastically abutted against the seal cover (24) and the ring gear disc (22, 6), and are elastically pushed against the row teeth (10) of the ring gear disc to engage with the tooth row (3, 9) of the ring portion (212, 52). The device can generate a tooth skipping sound to let a user know the reversing case, and has the advantages of reduced whole weight, convenient assembly, and simple operation.
C: A planter driven by a shaft of a walking tractor. A cam (7) with multiple embossments is sleeved on a shaft of a driving wheel shaft of the walking tractor. A ratchet wheel structure is installed on a planting wheel shaft of the planter. The ratchet wheel structure comprises an oscillating bar (2), a pawl (1), a check pawl (5), and a ratchet wheel (4) installed on the planting wheel shaft. The oscillating bar (2) is installed on the ratchet wheel (4). A return spring (3) is arranged on the oscillating bar (2). The pawl (1) is hinged on the oscillating bar (2). A driver cooperating with the embossments of the cam (7) is connected to the oscillating bar (2). The planter implements intermittent movement through cooperative use of the cam and the ratchet wheel, thereby bringing convenience to installation of a seed metering device of the planter. In addition, it is convenient for changing a plant spacing of the planter. A long-chain wheel and land wheel structure is cancelled, so that a driving manner is simple and reasonable, off-chain, stuck, and miss-seeding phenomenon and the like do not occur in a planting process, maintenance is convenient, and a fault rate is decreased, thereby improving reliability and working efficiency of the planter.
D: A three-ratchet wheel one-way clutch, comprising a driving ratchet wheel (1, 5), pawls (2, 6), elastic components (3, 7), a pawl base (4, 8), a front driven ratchet (12, 52), and a rear driven ratchet wheel (15, 55). One or more pawls (2, 6) are arranged on the pawl base (4, 8), and the elastic components (3, 7) are connected to the pawls (2, 6). The driving ratchet wheel (1, 5), the front driven ratchet wheel (12, 52), and the rear driven ratchet wheel (15, 55) are all connected to the pawl base (4, 8), and are all able to rotate relative to the pawl base (4, 8). When the three-ratchet wheel one-way clutch rotates along an unrestricted direction, the pawls (2, 6) move on the tops of the teeth of the front driven ratchet wheel (12, 52) and the rear driven ratchet wheel (15, 55), and the tops of the teeth of the driving ratchet wheel (1, 5).
Answer: B