This week, the overall grades of six machinery stocks are lower, according to the Portfolio Grader database. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

This week, Pall Corporation (PLL) falls to a D (“sell”), worse than last week’s grade of C (“hold”). Pall is a supplier of filtration, separation and purification technologies. The stock has a trailing PE Ratio of 31.40. For a full analysis of PLL stock, visit Portfolio Grader.

Lindsay Corporation’s (LNN) rating falls this week to an F (“strong sell”), down from last week’s D (“sell”). Lindsay manufactures and markets center pivot and lateral move irrigation equipment, as well as large diameter steel tubing, for use to irrigate agricultural crops. The stock also rates an F in Earnings Surprise. As of Jan. 17, 2014, 32.4% of outstanding Lindsay Corporation shares were held short. To get an in-depth look at LNN, get Portfolio Grader’s complete analysis of LNN stock.

The rating of The Timken Company (TKR) slips from a D to an F. Timken is a developer, manufacturer, marketer and vendor of products for friction management and power transmission, alloy steels and steel components. The stock gets F’s in Earnings Revisions, Earnings Surprise and Sales Growth. For more information, get Portfolio Grader’s complete analysis of TKR stock.

This is a rough week for Kaydon Corporation (KDN). The company’s rating falls to F from the previous week’s D. Kaydon designs, manufactures, and sells custom-engineered products for a variety of industries, including aerospace, defense, and industrial. The stock gets F’s in Earnings Growth, Earnings Momentum, Cash Flow and Margin Growth. The stock’s trailing PE Ratio is 37.20. For a full analysis of KDN stock, visit Portfolio Grader.

Briggs & Stratton Corporation (BGG) earns an F this week, falling from last week’s grade of D. Briggs & Stratton produces air-cooled gasoline engines for outdoor power equipment, in addition to designing, manufacturing, marketing and servicing these products for original equipment manufacturers worldwide. The stock gets F’s in Earnings Momentum and Margin Growth. As of Jan. 17, 2014, 14% of outstanding Briggs & Stratton Corporation shares were held short. For more information, get Portfolio Grader’s complete analysis of BGG stock.

Slipping from a D to an F rating, Hurco Companies, Inc. (HURC) takes a hit this week. Hurco Companies designs and produces interactive computer controls, software, and computerized machine systems for the worldwide metal cutting and metal forming industry. The stock gets F’s in Earnings Growth, Earnings Revisions and Sales Growth. For a full analysis of HURC stock, visit Portfolio Grader.

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.