The overall ratings of three Machinery stocks are down on Portfolio Grader this week. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

This week, Tennant (NYSE:TNC) falls to a D (“sell”), worse than last week’s grade of C (“hold”). Tennant designs, manufactures and sells of products used mainly in the maintenance of non-residential surfaces. TNC also rates an F in Portfolio Grader’s specific subcategory of Earnings Surprise. For a full analysis of TNC stock, visit Portfolio Grader.

This week, Energy Recovery‘s (NASDAQ:ERII) rating worsens to a D from the company’s C rating a week ago. Energy Recovery develops and manufactures energy recovery devices utilized in the water desalination industry. The stock gets F’s in Equity, Cash Flow, and Sales Growth. For more information, get Portfolio Grader’s complete analysis of ERII stock.

Sauer-Danfoss (NYSE:SHS) earns a D this week, falling from last week’s grade of C. Sauer-Danfoss designs, manufactures, and markets hydraulic, electronic, and mechanical components, as well as software and integrated systems that generate, transmit, and control power in mobile equipment. The stock also gets an F in Earnings Momentum. To get an in-depth look at SHS, get Portfolio Grader’s complete analysis of SHS stock.

Louis Navellier’s proprietary Portfolio Grader stock ranking system assesses roughly 5,000 companies every week based on a number of fundamental and quantitative measures. Stocks are given a letter grade based on their results — with A being “strong buy,” and F being “strong sell.” Explore the tool here.