Seed and fertilizer metering mechanism for agricultural drilling machines

An agricultural drilling machine comprising:

• a hopper for seed and/or fertilizer, said hopper having downwardly-converging front and rear walls and a bottom portion which defines a plurality of exit openings spaced from one another lengthwise of said hopper through which seed or fertilizer to be drilled by said machine can flow;
• a plurality of metering mechanisms, one for each of said exit openings respectively, to provide a metered flow of seed or fertilizer from said hopper through each of said exit openings;
• and
• collecting cups and associated conduits positioned below said plurality of metering mechanisms to receive each of said metered flows of seed or fertilizer and to deliver said metered flows to the ground prepared by said soil-working members;
• each of said metering mechanisms comprising:
• a rotatable metering roller connectable to a drive and mounted below its respective exit opening of said hopper, said metering roller having a compressible surface portion;
• a flat glass metering plate;
• and
• a holder for said metering plate connected to the front side of said hopper and extending generally vertically from said hopper to a position below said respective exit opening, said glass metering plate being fixed to said holder in a substantially vertical attitude adjacent to the compressible surface of its respective metering roller at a position forward of and below its said respective exit opening of said hopper, and said glass metering plate being positioned in substantially tangential relation to and bearing against the compressible surface of its respective metering roller so as to define therewith a downwardly tapering nip having unobstructed communication with said hopper through said exit opening, the direction of rotation of said metering roller by said drive during use being such that seed or fertilizer in said nip is fed by said metering roller through said nip and past said glass metering plate for discharge downwardly to said collecting cups and conduits while said glass metering plate permits visual monitoring from the front side of said hopper through said glass metering plate of the flow of speed or fertilizer between the said glass metering plate and its respective metering roller.