US Patent 10030690 High-negative-pressure composite hard suction cup

The high-negative-pressure composite hard suction cup has a main member made of a hard, composite material tightly joined to a highly flexible washer made of soft plastic along a bottom side. The main member is configured with a vacuuming mechanism to another side. The vacuuming mechanism includes a piston chamber, one-way valve, piston assembly, and spring. A vacuum alarming assembly is configured on the piston assembly. When a degree of vacuum between the hard suction cup and an object attached is less than satisfactory, an audio or visual alarm is issued and an alert marking is revealed to notify a user to take appropriate action so that the hard suction cup remains reliably attached to the object.