Ram-ploughs

Introduced: September 1968

Last revised: January 2006

Full Title

Machines which completely free the mineral from the seam > Mineral freed by means not involving slitting > by adjustable or non-adjustable planing means with or without loading arrangements > Machine propelled along the working face by cable or chain > Ram-ploughs

Classification Context

Section:: FIXED CONSTRUCTIONS
Class:: EARTH OR ROCK DRILLING; MINING
Subclass:: MINING OR QUARRYING

Top Applicants

Top 10 applicants by patent filingsfor class E21, 2013–2023, worldwide · Source: EPO PATSTAT

HALLIBURTON ENERGY SERVICES GROUP US 26,607
PETROCHINA COMPANY 14,382
SINOPEC (CHINA PETROCHEMICAL CORPORATION) 10,137
CNPC (CHINA NATIONAL PETROLEUM CORPORATION) 6,517
BAKER HUGHES US 6,269
SCHLUMBERGER TECHNOLOGY US 5,929
SAUDI ARABIAN OIL COMPANY SA 5,880
SOUTHWEST PETROLEUM UNIVERSITY 4,477
CHINA UNIVERSITY OF MINING AND TECHNOLOGY 4,357
SCHLUMBERGER TECHNOLOGY NL 4,219